Ok, I have a 1990 n/a that i bought in New York. The guy claimed the engine was blown but his story sounded fishy. The car only has 75k so as soon as I got it home I did a compression test. Got 90 psi out of both rotors without even holding the throttle down but I didnt remove the valve from the the compression tester. I also tested it while holding the relief and all the pulses was just about even in both chambers. So I put a battery in it and the car started right up but wouldnt stay on unless i give it gas. The first thing that came to my mind was that the primary injectors were clogged
So as I was replacing them, I noticed that the gas was a little dark, so I drained the tank and put a new fuel filter. After I got everything back together, It didnt make a difference. It will start up everytime but breaks up at low rpms unless I put enough load on it to make it sound clear at low rpms. At higher rpms it sounds very good and revs strong. My next step was replacing the fuel pump but before I do that I want to see what you guys think the problem could be.

 

Perhaps TPS is way out? Or you have a vacuum leak somewhere?

I had a similar problem, turned out to be a massive split in my intake pipe after the afm.