Stalling at idle especially in reverse or with the A/C on?

1992 GMC VANDURA
210,000 MILES • 5.7L • V8 • 2WD • AUTOMATIC
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CHRIS MCCAULEY
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Vehicle listed above stalls at idle but mostly at low speeds in reverse or with the A/C on. I bought the van and drove cross country pretty well, now it has issues. At stoplights it seems like the van is in a very low idle, the oil gauge fluctuates very low the battery fluctuates and the lights on the dash and front headlights dim with the fluctuations. Van will shut off but turn on instantly usually just to shut off again, I had a shop replace the IAC valve but nothing else but have had alternator and starter replaced within last year or two, I also went through and cleaned the Injectors and cylinders with a toothbrush. Any ideas on how i can get this thing to idle without stalling again?
Aug 8, 2023 at 2:01 PM
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STRAILER
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I would service the throttle body and check for vacuum leaks, also can I ask if the check engine light is on? Here are three guides to help us fix the problem:

https://www.2carpros.com/articles/stall-at-idle

and

https://www.2carpros.com/articles/throttle-actuator-service

and use this guide when the engine is cold only:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Please go over these guides and get back to us.
Aug 10, 2023 at 11:10 AM