IAC problem 1986 GM 5.0?

[Bud]

You can try giving the IAC a few smacks with something solid when its acting up. If that repeatedly clears it up, pretty safe to condemn it.

Thanks I did try the BFH (big f---ing hammer) method-no results there.

[miamibob]

Have you removed the IAC, cleaned it (or better yet replace with an OEM one) along with cleaning the ports it bolts too. Also, clean out the "hole" on the inside of the throttle body along with the butterfly - inside and out. Let us know how things are after that. Of course, if you altered things by turning "idle screws" all bets may be off until that is returned to original status. Take off the battery after al this for 15 mins or so and restart to clear memory.

[Bud]

To summarize-turns out it was the IAC valve that was the prob. It had me fooled cause it didn't have the symptoms that most told about. It ran fine till it warmed up then revs increased a lot-hope this helps someone else.
Bud

[sly]

here's the idle procedure for an F150: http://www.grandmarq.net/sly/F150%20...0Procedure.gif (use the 5.0L EFI column)

the only change is you don't need the feeler gauge for the panthers (at least that's what I've done with mine and it works like a champ without the feeler gauge and doesn't work so well with the feeler gauge)