Dies when not given gas?

2006 BUICK RENDEZVOUS
158,000 MILES • 3.5L • V6 • 2WD • AUTOMATIC
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WHOPPEY
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I'm trying to help a friend who recently got screwed over by a very expensive "mechanic". The main problem he's having is the car idles kinda rough and it dies whenever he lets off the gas at red lights, stop signs, etc. I was thinking a dirty idle air control valve or throttle body. I checked for vacuum leaks and everything was good there. Its got newer sparkplugs and wires from previous mechanic.
Aug 29, 2025 at 1:15 PM
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STRAILER
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So we need to check the engine compression which will cause this kind of issue. Also, you must make sure the correct spark plugs were installed. Here is a guide to help with the testing

https://www.2carpros.com/articles/how-to-test-engine-compression

These are the spark plugs that need to be installed.

ACDelco 41-101 (Professional Iridium) - this is the OEM plug GM spec’d for that engine.

Gap: 0.040 in (1.0 mm)

Please upload what the spark plugs look like so I can see them to tell what might be happening as well when you get back to us.
Aug 29, 2025 at 6:05 PM