Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
I had a trail blazer two days ago with the same problem. It turns out the low idle and shuddering was simply a dirty throttle body. The throttle body on this model is susceptible to carbon build up because of the crankcase re-circulation system. The repair manual's procedure is to remove and clean the throttle body, but we were able to clean the throttle body with come Wynn's throttle body cleaner (STP or any decent brand of throttle body spray will work). Follow the indications on the product, but basically you will open the throttle by hand with the engine off and give it a generous spray to try to knock off the carbon inside. Then you can have a helper inside the car start the engine while you spay cleaner in the throttle body. Use eye protection! That stuff is horrible when it gets in your eyes! The engine will try to stall so your helper will have to keep it running by reving the engine wen it tries to die. When you are done, drive the vehicle and get the RPMs up a little to run the carbon through and the idle should pick back up on it's own.
I don't think you should worry about doing an idle re-learn, but if you would like to try I can give you the procedure.
I just wanted to check in and see if you needed any additional information. I hope that I have been of some assistance and would appreciate a positive rating if it have. Thanks!
Ok. Let me know if you need any help.