94 Grand Am 1 and 3 cylinders not firing

Try a coil.

Unfortunatley, there are times when You can only be 90% sure. Todays cars are not the easiest thing to diagnose. Ask them if it isn't the fuel injector(s), if they will cut you a deal, as more diagnosing will be required.
No one wants to pay for somthing that isn't certain. Any quality shop doesn't want to recommend the wrong thing. The shop wants to fix the car. They want a happy customer. Patience is needed on both sides.

I'm curious if this is a 2.3 quad four motor. Those are common for ignition troubles. Fuel injectors aren't very common, but you have a lot of miles on it. Are they sure it is fuel related? ? Not spark or compression? Was they cylinders checked for compression?

Now you said cylinders 1 and 3 will not fire. How do you know this? When they put a tester in place of the plug you dont get spark? If that is the case, then dont change fuel components for an ignition problem. One of your coils fire the 1 and 4 cylinder, and one fires trhe 2 and 3 cylinders, so I suspect it isnt a coil. With everything you have descibed, I would suspect the crankshaft sensor, or even the pick ups for missing teeth.

I guess you need to know what their logic is regarding the fuel injectors and why fuel is the assumed problem.

My experience with this motor is loss of ignition. Again with 150,000 miles, this may or may not be it. Having said that, I would be suspicious of the coil housing first. There is a plate on the top of the motor that is held down with 4 or 6 bolts. After that is removed, you can see the spark plugs. If it was mine, I would look at the condition of the boots that snap onto the coil housing and into the plugs. I have had these short out. The coil housing that is attached to the metal top plate has been a common issue. Less common, but not uncommon are the 2 coils that set inside the coil housing. These are common enough that you may have done these in the past, and maybe the part has a warranty.

It would be worth taking to the shop in a non-threatening manner to understand why they are recommending them. In the past we have made up a set of ignition wires with a spark tester to run from the plugs to the coil housing so we could see spark loss while it ran while the housing was not actually installed. Often communication can get lost between the shop and customer. It's important that you ask questions and get answers you understand what is happening. IF you can't get good communication, it will be a matter of time before you lose trust. I suggest you talk to them and have a clear understanding of why they recommend injectors and how they tested for spark. IF they lose patience or won't give you the time of day to talk, maybe a different shop can help that specializes in diagnostic repairs. Good shops are cheap, but worth it in the long run.