my 89 has a 305tbi with a new fuel pump plugs wires cap rotor and coolant temp sensor and yet still i have the problem of the car is fast and pulls HARD when it's cold, but as soon as she gets warm or runs for about 7-9min it looses power shifts real sloppy(not firm and at like 1500rpm) it just becomes a slug. I have serched and read everywhere and no where can i find a straight answear of what is wrong. best i have got is replace the egr, ecu, and coil. but i would rather fix it not just throw parts at it. Also the tbi will be removed due to im going carb and a 383, but in the mean time i would like to feel like im driving a camaro not a prius

 

coil would probably be giving you issues all around, cold or warm. i'd check out the egr, as it may be getting stuck. try hooking up a vacuum pump to it and see if it'll hold pressure. it may be worthwhile to have the car hooked up to a good mechanic's scan tool and see what your sensors are reading - one bad sensor can cause a world of issues.