Here's the deal, When the car warms up it starts to miss and back fire through the exaust and intake if revved far enough. Like it jumped a tooth on the timing chain. It runs great til then. It has new plugs, wires, cap and rotor. I have good fuel pressure the whole time. When I go to my dads and put it on the scanner It shows my intake air temp switch going from 360 degrees slowly down to -16 then starts over again even when the switch is disconnected! It should read -40 when disconnected. The egr electrical switch is not being grounded so it's not giving the egr vaccumm. It was a 305 car, then we put a 350 in it with all the 350 knock sensor, injectors and other sensors needed. The computer is out of a 93' caprice tbi 350 car. So I'm down to the computer isn't getting a ground somewhere or? It failed nox emissions bad and that's when we found out about the egr and air temp sensor problem. The new thing is the car will die when driving and not start for 20 min or so. I'm thinking either the distributer pick up coil is going out or there is a silinoid on the far driver side firewall that is getting very hot when the car is warm, like you can't touch it hot. Not sure what silinoid this is though. Oh and the timing is good.

recheck plug wires - make sure all are securely on plugs, recheck firing order, make sure all wires have no breaks/shorts in them (check continuity).

sounds like pickup coil or the ICM inside the dist. (Ignition Control Module)

Solenoid? I think you mean relay. One is for the electric fan, one is for the fuel pump

Plug wires are good and tight.
And yes I meant relay, I'm going to replace that just in case
I'm thinking ICM right now but might just replace them both just in case (pick up coil).

Still very confused on how my computer is reading and not sending proper grounds to some sensors, I am getting the 5 volts at the air temp switch and at the computer.