High idle on 4.3 vortec

[gmoutdoorsman]

My 1998 4.3 seems to be idling high and keeps throwing idle air control DTC's My IAC valve seemed to be stuck (carbon?) so I just picked up a used one from a junkyard and cleaned it really good.Still idles around 1100 rpm in park and 2000 in neutral.Runs fine sometimes studders off the line.A new IAC is my next thing ill try. Any suggestions?? Thanks

 

[gmoutdoorsman]

It sounds like my intake manifold is sucking air at an idle but i cant for the life of me figure out where from.I was told if i spray carb cleaner around where i think the leak is it'll idle up indicating i found the leak

 

[twomanymontes]

The gasket under the throttle body is common to fail and cause a vacuum leak. Also check all hoses and around the edge of the intake itself.

 

[gmoutdoorsman]

Think i found it. Its the gasket/O-ring around the CPI plug behind the Throttle body.Just guna do all the Gaskets from the upper Manifold up