2.9L Surging

[EvanCole45]

Hello,
My 1988 2.9 L engine is surging at idle and I'm wondering what could be causing it? After driving a short distance and coming to a stop, the engine will start to bounce between 400 and 1000 rpms until I turn the engine off. When I start the truck back up it idles fine until I drive for another minute or two then come to a stop. I've already checked all of the obvious vacuum hoses and it has had a small vacuum leak that I can hear for about 4 months but it just now started having the surging issue so I don't think it's from that very minor leak.

I'd appreciate if someone could give me some other possible causes of the surging, thanks!

 

[rusty ol ranger]

Remove and clean/replace your IAC (idle air control) valve.

Id also chase down that vacuum leak....better to not leave any stones unturned.

 

[EvanCole45]

I just removed the IAC and it was perfectly clean to start with. Now what?

 

[sheep herder]

I just removed the IAC and it was perfectly clean to start with. Now what?

It's clean but does it work?

 

[EvanCole45]

It's clean but does it work?

I appears to be working. The engine idles normally until I drive it for a few minutes then let it idle again.