It could be as easy as cleaning or replacing the I.A.C. (idle air controller) it may need to be replaced if you can not clean it good. When was the last time to replaced the fuel filter? if it persists wait until dark lift the hood, have someone start the vehicle and raise the idle watch for an arc, identify the wire and replace it. Another thing to check would be the throttle body gasket get a spray bottle put it on mist with water in it, start the vehicle, sprat around the bottom of the throttle body, if it bogs down replace the gasket, by removing the 4 bolts lift the throttle body replace the gasket and replace the bolts.
Appears you've done some homework. Try taking out fuse # 10 and fuse # 28 under the hood. Keep them out for 30 minutes, this is the way most of us reset of the PCM on our platform after a TB cleaning. I'm betting the PCM needs to relearn correctly. Next time you're cleaning the throttle body, unhook those fuses prior to doing anything. By the time you're done cleaning, sufficient time will have passed.
When was the last oil change --check and test the and or clean the camshaft position actuator solenoid its on passenger next to the powering steering pump the connection sometimes gets oil soaked and or the screen get clogged --if oil is old or low effects the sensor check and test the camshaft position sensor also it also is affected by oil ---other problems can be a plug or coil failing
SOURCE: idle too high on a 06 cobalt
when you clean it make sure that you hold the butterfly open so you can get the spots clean that need it. If there is anything in the way the butterfly will not close. Just a small bit of dirt will do this .
SOURCE: 2002 chevy trailblazer has rough idle
it could be an o2 sensor. it could also just need a tune up
SOURCE: 1989 Chevrolet C1500 with 5.7L V-8. Engine dies
fuel pump is working but when accelerating it doesnt pump enough fuel up to the engine then it will fall on its face if it is a electric pump you may have to drop the tank if it is inside and replace it if it is on the engine replace it thats what is exactly wrong with it
SOURCE: I own a 2002 Chevy Trailblazer with 4200 vortec
Do you know if the plugs were changed, a bad or broken plug will also cause rough idle and slow acceleration?
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One possibility is weak coil pack or bad spark plug. You have the engine scanned with a professional scan tool to see if there are any stored codes that a handheld scanner will not pickup
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