Ever since I took my stock 305 out and swapped with the 350vortec motor (kept the TBI), my car will idle fine at start-up and sound healthy until I try to take off. Sometimes it just bogs down and tries to die when I try to accelerate and other times it will idle UP and then DOWN and UP and DOWN and then sometimes it will idle down hard enough that it will kill itself. Any thoughts? I've been fighting this for a year now...

 

Sounds like my engine day one of mods. I would start with a datalog and see what your sensors are seeing.

what is coolant temp when you try to move car? If you allow it to come up on temp to 165F(closed loop) is the result the same?

 

tps or IAC but it sounds like a flat spot in the tps. Or the MAP sensor is shot


My 92 tbi does the funny idle thing where it goes up and down and bogs on me sometimes on the start but I have a manual so I can feather the clutch.