Yes ihav e 2003 envoy with 4.2 liter an it has started idiling rough
There are a few things that you can do, do get it idling correctly, and it's fairly inexpensive.
1. Clean your throttle body with throttle body cleaner, with the battery disconnected. Needs to be shiny. When finished, drive around for 20 minutes or so with all accessories turned off, so the computer can relearn the newly cleaned TB. About $7 for the cleaner
2. Replace your spark plugs with A/C Delco 41-103, will idle better with this plug. Around $7 ea
3. Replace your upstream 02 sensor, the one right after the exhaust comes out of the engine, easy to replace. Between $67 and $80, try to stay away from Bosch.
4. Replace your fuel filter around $15 or less.
5. Check your vaccum lines for leaks.
Didn't disturb IAC connection by chance did you. ?
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