I have a 94 chevy 1500 4.3l 2wd w/t 196,000 i have replaced the cap,rotor,wires,,plugs,ff,coil,o2,both TBI injectors,fuel pressure regulator,both temp sensors and the IAC. The codes for the temp sensor 15 open circuit or short and IAC 35 not able to set idle will not reset and any time i try the truck doesn't want to start and will just turn over and then eventually start(roughly)and the light will be on.The idle smooths out and if you throttle it just right it runs perfectly but if you pop the throttle it will stumble and almost die it really acts like its over fueling and it seems to be at its worst when it warms up almost perfect when cold and oh yeah my temp gauge heats all the way up to 3/4 then fluctuates anywhere between 1/2 and 3/4 while driving.replacing some of this stuff has made it run better especially cold but i'am running out of ideas anything would be much appreciated

 

You might try knock sensor replacement I don't know other than throwing good money after bad.