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I have a 95 GMC c1500 pickup w/5.7 & auto. The problum is as follows. When staring with a cold engine it runs fine but, as soon as the engine warms up to operating temp (only a couple of minits) it will hesitate/stumble around 1200 to 1800 RPM yet it will idle just fine. It does not matter weather it is under a load or not. Check engine light is not on & has no codes present. It was doing this when I bought it with 161000 miles. have replaced the following mostly because it really needed it; cap, rotor, coil, plugs, plug wires, map sensor, tps, fuel filter. Also have checked the engine gound wires & checked for vacuum leaks. Since it runs smooth at idle I don't beleive it has vacuum leaks. The spary pattern for the injectors seems to be fine. I have not checked fuel pressure but since it accelerates fine under full thottle I did'nt think theres a problum with the pump. Is anyone here familar with these symptoms? Are there common issuses with the base plates wearing out on the throttle body? Or do the distributor bushings wear out? Im stumped!!!
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thanks for your responce guys, to Carpenterbill---- I have been courious about the EGR system, I can move the EGR diapharm with my finger but I know it is not a good test. to 99silverado----- since my truck accelerates fine under full power logic tells me the cat converter is not blocked , and as for the guys at AutoZone----- are you really going to trust what they say????? All they are good for is giving codes.