95 problem

i have a 95 chevy 4.3L 5spd that hesatates at a constant speed it idles fine & if you floor it the power is there. i have replaced plugs, wires,rotor, cap, fuel pump,egr valve,egr vacuum solinoid,pvc,fuel filter,gas cap.it also only does this once engine is warm.i am lost please help.

Could be an O2 sensor, if they're over 100k miles just replace them, they don't usually last much longer than that. If less, check the waveform on an oscilliscope.

the o2 sensors are fairly new.i had to use the truck the other day and i found once the engine was at normal temp it didnt want to idle. it would start to stall the the rpms would shoot up to like 1200. it does this for awhile and then it dies. any ideas on what i am missing. :banghead:

Did you check for plugged catalytic converters yet?
Fuel pressure?
How about a smoke test for the EGR, PCV, and Intake systems?

yes i have checked for blocked cat and i have checked all vaccum areas.fuel pump is also at the right pressure.