We just replaced the head gasket and sealed with silicone and new gaskets. After our process was complete we discovered the engine idle would go from 1,000 rpms for 8 sec to 500 rpms 8 seconds sometimes even 350 rpms about. What did we mess up?? We already checked the status of the ignition coils they are good read 6.6 on the ohms of a voltage meter. If anyone has a check list of possible issues that would help so much. video of my explanation
The obvious thing to check in case of hunting idle here is unmetered air or a vacuum leak.
A quick (not comprehensive) checklist:
Are all intake-side hoses connected?
Possible suspects: brake booster vacuum line, crankcase ventilation line, EGR line...
Is the idle air control valve functioning as it should?
Are there signs of an obvious leak?
If it's bad enough, there should be an audible hissing sound around the engine