I have posted about this on here before and I thought I had it fixed, but I went on a classic car run the other day and had the same issues.

I have a 1985 Iroc with a L89 out of a 1989 vette. It has bigger injectors and cam and throttle body. I drove it 30 miles and everything ran fine. Took off on the next leg of the run and she started to die when the rpm's would fall below 2000. I kept is revved up and floored a couple of times and it kind of seemed like it came out of it. Don't think it really did though. Anyways it would die and I would coast to the side of the road and try starting and it would turn over and not fire for a couple minutes, and then it would start and I would keep her revved up and take off again. Whenever I would slow down she wanted to die and I think the temperature would start to rise. I have two electric fans and an aluminum radiator so it runs about 180 degrees. I have put in a fuel pump, ignition module, coil, cap, rotor, and thought I had it fixed. But it seems I am going to have to add more stuff. Any Ideas on what it could be?

 

I am maybe leaning towards a new throttle position sensor or another fuel pump.