Strange Intermittent Idle Fluctuation

Today I was sitting at a light and noticed that my idle was unusual. Instead of being around 600-700, it was bouncing between 1000-1100.

Thats normal rpm for startup, but the engine was already warm, and it never goes up and down like it was.

I turned off the radio and made sure nothing was on that would cause a load. It idled like this whether I was in neutral or in gear with the clutch in.

Then within a couple minutes it stopped, and the idle went to 600 and seemed to be normal again. And I couldn’t repeat it once I got home.

The MAF was cleaned in December. If it were a vacuum leak it shouldn’t go away. IAC maybe. Any ideas?

 

Clean the IAC/Throttle body.

Might be a bad IAC or TPS or MAF. Those are the main culprits.

 

Is the IAC PN 22270-75040 correct? I'm not going to replace my IAC immediately, but at some point I should buy one since that seems like something that would get discontinued.

Last time I saw my throttle body 5 months ago it didn't look dirty, but the IAC could be.

 

I found for a 4cyl 97:
Cali 22270-75051
Fed 22270-75040