I just bought my wife a 1990 F250 with the 5.8 litre. It has an intermittent issue with a surging idle, as well as surging at LOW speeds, that clears up as soon as the gas pedal is pressed.

I've been told that it could be the IAC or EGR, but I cannot find either of these dang things. I have looked all over under the hood. I can find them in a Volvo, though.

Any help would be appreciated, and will make my wife happy.

Thanks

 

It sounds more like an IAC or TPS issue to me.
Both are attached to the TB. Testing & cleaning can be found using the search feature or a Haynes/Chiltons manual (recommended)
Pulling your computer codes is highly recommended. Visit www.fordfuelinjection.com to learn how.
Cheers,
Popa Tim