Pulling alternately left and/or right

Worn half shafts do not cause a pulling problem. There's two things to consider. Something is moving due to a worn part, and that results in the alignment changing, or the tires on the front do not have equal rolling characteristics.

The place where I would start is by observing when the pull occurs and what I can do to affect it. Most commonly a tire pull will cause the vehicle to pull one way during moderate to hard acceleration, and it will pull the other way during braking. To verify that is due to the tires, switch the tires / wheels from side to side, then the pulls will go the other way.

When a worn part is overlooked, the numbers on the alignment computer will be quite different when the vehicle is set up the second time. Pay particular attention to "caster". Caster is not adjustable on most front-wheel-drive vehicles, and it has almost no affect on puling or tire wear, however, it still gets measured automatically by all alignment computers. When a part is worn, changes in the caster readings prove that something is not being held firmly in place. "Camber" and "toe" readings will usually have changed too, but changes in caster are easier to spot.

If a worn part is causing this problem, you won't see a change in the direction of pull when you switch the tires side to side. If the pull is still affected by accelerating and braking, the rubber lower control arm bushings become good suspects. The mechanic won't be able to see any movement when he pries on those if the van is jacked up under the control arms. Most drive-on alignment hoists use the type of jacks that do lift under the control arms. The jack needs to be placed under the frame rails during the inspection, then it must be repositioned later under the control arms when setting the van up for the alignment.

A badly worn strut can cause this symptom too, but you'll usually have been hearing intermittent clunking noises for a long time. This type of wear is different than the oil has leaked out and the van bounces a lot. This type of wear comes much later after that strut has been ignored for many months. To find this, the van can not be jacked up with the jack under the frame, as in the previous procedure. Doing so will make the front suspension held up by the fully-extended strut. You won't be able to cause and see any objectionable movement with that tension on the strut's shaft. The best way to find this is to raise the vehicle just a few inches with the jack under the frame, then tug in and out on the top of the tire. You'll feel the tire, wheel, and spindle clunk back and forth if the strut is worn.

You can also provide a clue for your mechanic by observing what happens with the steering wheel. First, observe if the steering wheel rotates by itself when the pull occurs, and note whether it rotates the same way as the pull or the opposite way. If the steering wheel stays perfectly centered when the pull occurs, that is also a clue, and you will have to turn the wheel yourself to correct for that pull.

I was going to mention the steering gear mounting bolts, but if those were loose or the rubber inserts were worn, that will not cause a pull or drift. It will cause the tires to follow the bumps and ruts in the road, and you would have to counteract that by turning the steering wheel. You'd feel thumping in the steering wheel too.

Correct suspension ride height also affects tire wear and handling even when the alignment appears to be perfect. Sagged front coil springs have less detrimental affect on the handling of your van compared to other car and truck models, but if rear helper springs raised the back of the van significantly, that will lower the front caster readings. Caster is mainly involved with directional stability and the steering wheel self-returning to center when you let go of it after going around a corner. As the rear of the van goes up, caster goes down, and as caster goes down, you'll need to be making more small steering corrections at highway speed. The lower caster gets, the more tiring the vehicle is to drive since you can't just hold the steering wheel with one finger and buzz down the road. As I mentioned earlier, caster isn't adjustable on your van, and there really is no need to adjust it. 3.0 degrees is common and typical, so what you listed is fine, and if the numbers printed out in green, they are in specs.

A worn wheel bearing would have presented other symptoms before it got to this point. You would have heard a loud buzzing noise for many months before any slop or play developed. The exception would be if the large axle nut was loosened. That is what holds the bearing together. Tightening the nut would take the play out of the bearing, but it would always be noisy after that.

Anything else in the steering system should include clunking or thumping felt in the steering wheel. That includes the small universal joints in the steering shaft, and the spool valve inside the steering gear.

We always think about something coming apart in the rack and pinion assembly, but that too would be met with binding and / or clunking that you would feel. In ten years as the suspension and alignment specialist at my local Chrysler dealership, the only rack and pinion steering gear coming apart I ever came across was in my mother's '95 Grand Caravan. That one was bad enough the van couldn't be driven. Turns out someone else had it apart years earlier and didn't reassemble it correctly.

Most times we now install "quick struts" which include new coil springs and upper mounting plates. Parts cost more, but labor time is greatly reduced and there are no safety concerns with escaping compressed springs. In the past it was customary to take the spring and upper plate off and reuse them when replacing the struts. If that is what was done, the center hole in the upper plate could be worn larger and could have been overlooked. That could allow the strut's shaft to slide left and right when you hit bumps in the road. You may not feel that when it occurs, but it will change "camber". Camber is the inward or outward tilt of the wheel as viewed from in front of the van. Most importantly, a tire will want to pull in the direction it is leaning. Besides adjusting camber to specs to reduce tire wear, it is important that both sides be set nearly the same so their pulls counteract each other. I always had my alignment computer set to read two digits after the decimal point. That provides more accuracy but it takes longer to set each wheel perfectly. The issue still remains here that something is changing, not simply set wrong. The nuts on the tops of the strut shafts sit in a fairly tight pocket, so on your model, a worn-out hole is not a real good suspect. What is a better suspect is the strut towers are rusted from road salt. Those towers are the sheet metal the upper mounting plates are bolted to. To check for this, tug on the top of the front tires while the alignment equipment is set up. If the camber reading changes significantly, it has to be due to something that holds that wheel in alignment, and anything that is changing will cause intermittent pulling.