Preparing to drive home after a St. Patrick's Day party (one beer-don't judge,) my 2001 V6 Alero started promptly, but idled at 2500 rpm. I tried kicking it down (from my old days) and was unsuccessful.

The engine speed dropped momentarily when I shifted into drive (both feet on the brake) but then promptly increased and for the remainder of the short drive home, I didn't need to touch the accelerator to go 30+ miles per hour.

When I got home, I shut it off (really high idle-3,000 rpm in park, car at normal operating temperature) and restarted it and the car returned to behaving normally.

I'm familiar with intake leaks causing uncontrollable idle and haven't been able to find any issues so far. Likewise, the car hasn't "misbehaved" similarly since.

I didn't get any sort of check engine light or other warning and have not checked the archive yet. I don't have any fluid deficiencies that I could detect. It's almost as though the car momentarily "lost its mind," but now remembers.

Things that go away on their own come back on their own. Has anyone had a similar experience and found a cause or explanation for this behavior?

Thanks.

 

I had a similar problem when I cleaned the throttle body in my 2001 Alero V6, idle went up to 3000 RPMs. I shut it off and looked over my work and realized I forgot to plug the power connector to the Idle Air Control Valve back in. Strangely I got no CEL/SES lights when this happened, even though a failed IAC valve should cause the light to come on. You might want to make sure there's a good connection there, the contacts may need to be cleaned or the connector could be loose.