Starting and run problem

I'll need to get back with you after Christmas. It's hard to see connections with out removing the lower pan and opening the engine space. That would make since if it is intermittently making good contact, just odd the way it behaves. Why does it always start when cold. It does have a cold start valve, but it doesn't seem to have any effect when I disable it at temperature. I haven't had any coils fail as of late, but it will just shutdown while driving, may or may not restart right away. It may run really well or run rough which could be consistent with a poor ground. I might have to add my own grounding cable. Thank you for your time, I'll get back with you.

I checked the ground resistance from battery to block, battery to body, body to block with zero resistance. I’ve checked the ground cables both visually and physically for corrosion and security, and found no deficiencies. The van ran well today, but I had intermittent tachometer failures for the first time ever, with no indication of other malfunctions. The tachometer is an integrated in the instrument panel, and no other readings were affected. (On my 1969 Mustang I would attribute this to a coil and or a connection problem being that it is an aftermarket tachometer I installed. Two wires which I can see.) There are three other ground leads/wires, besides the main cable, at the battery positive post. There is no way to follow those leads. I only know one lead goes into the cab somewhere.

Well, I spoke too soon, just took the van out to the beach. I had more tachometer erratic failures, but with momentary engine interruptions at the same time. When I sensed engine failures this time, I downshifted “which appeared to help” keep the engine running. Keep it in second gear, 5,000 rpm, to get me home. Ran well while at idle in the driveway! What do you think about an alternator failing?

I need to proof read better.
There are three other ground leads/wires, besides the main cable, at the battery "negative" post.
Well, I "spoke" too soon, just took the van out to the beach.

FYI, per my wiring diagram: There is a sensor (Camshaft Position, CMP Sensor) which provides input to/from/to the ECM and the Ignition Coil Power Output Stage that provides power to the Ignition Coil. (The Ignition Coil Power Output Stage "I think" is the base of the coil assembly, which I believe is where the failure is in the coils) The CMP also has input to the Distributor Rotor.

It took "some searching", but I found some on Ebay under the description (Distributor Ignition Pickup, $56-$101). I don’t expect to get it until about Jan. 5th 2019. Pending on the weather, how quickly I get around to installing it. I’ll get back to you then.

I'm not sure that the compatibility chart correctly identified this part to my vehicle. It would put this pickup at 180 degrees out of rotation for a five cylinder engine. I can see, that if you have an "even number" of cylinders that the way the distributor cam is designed that could work. But with an odd number of cylinders that doesn't seem possible. Can you verify or confirm? However the new pickup looks like the same "pickup" as shown in the parts breakdown in your image and in my manual. I put the new pickup in and it would not start, although it did fire in a cylinder or two. So I put the old one in and it started and ran well until is stalled and wouldn't restart until the engine cooled for several hours.

I'm not familiar with the nomenclature reluctor. Could you describe it for me?

Well, I got the truck to run with the new ignition pickup. However, I had to shift the distributor housing about 20 deg.” Counter clockwise”. The problem now is, I have no way to secure the distributor housing to the block. The adjustment slots in the housing no longer line up to the taps in the block for the locking bolts. So the timing can change or the distributor could just fall out. It only needs to slide out about a quarter inch to disengage with the cam.

So, I started the truck and let it idle for thirty minutes without incident (idle rpm increase excessively with temperature). And, I could not accelerate the engine with out it stalling. The advance doesn't work correctly. I tried minor adjustments without effect.

Pictures show the original Hall Effect Sensor/CMP, with reluctor at center.

The new sensor didn't come with a new reluctor, I'm using the original shown in the photo.
I did a new search on eBay using Hall Effect Sensor vice a CMP for my model and year and came up with a sensor that looks like my original and is "also" listed as compatible with my vehicle. I should expect it on Jan. 15.

EBay, Throttle Position Sensor Walker Products 200-1312 fits 1993 VW EuroVan 2.5L-L5

Just FYI, The Throttle Position Sensor "is not" the right part! However I found a Distributor Impulse Transmitter Kit BOSCH 1237031296 that is correct however, it looks exactly like the old one, but when I install it, the reluctor will not pass through the pickup slot. The rotor will not rotate without damaging the transmitter as it is. It is only off a fraction, maybe.01 inch. Waiting for a response form the seller to get back with me!

I had given up on finding the correct part under the nomenclatures I was using, and decide to look up a complete distributor, and while scrolling through the offerings this transmitter kit came up.

Happy Day, the new distributor works so far, well, at least for more than just a few miles. Ironically I found a new distributor at about a third of the cost ($38) of Distributor Ignition Pickup/Hall Effect Sensors that fortunately I was able to return. The truck “should have” another 60 to 80,000 miles. I’m going to get an extra distributor and keep it in the truck with a 5mm allen wrench, a 10mm socket and a coil ( it's an easy fix). Thanks for your help. Hope your day goes well.