GMC Repair: 1995 GMC Jimmy Vortec, throttle positioning sensor, gmc jimmy

Question
I have a 1995 gmc jimmy slt vortec with about 135,00 miles on it. Lately, either at idle or very low speeds, the tachometer has been fluctuationg at very low rpms (around 500), and the vehicle has died on me twice. The oil needle also goes up and down along with the tach. It has a history of getting the EGR Valve cleaned, but no other problems at all. Also, I had another jimmy same year -not an slt vortec- that had the same problems. When I pull out the Throttle Positioning Sensor it immediately smooths out, the tach jumps to 2000 rpm and stays consistent, and it runs fine. Any suggestions would be appreciated. Thanks.

Answer
Check the throttle plate for a blackish residue and clean off BOTH SIDES of the throttle plate as well as the throttle bore itself. Also locate the small IDLE AIR BY-PASS HOLE just in front of the throttle plate and spray some aerosol cleaner in it. This is quite common occurrance.


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