Not Idleing properly, but fine under throttle.

[acarmody]

Engine is an Ecotec, and like the title says it runs fine but idles a bit rough, and also seems to have very little power at idle. Like if I am backing out of the driveway, release the throttle and spin the wheel, it can drop a lot of RPM to near stall. Or even just coming up to lights it can drop RPM coming to stop. Also it sounds like its missing when your just idleing there, not seriously but enough to worry me.

I've replaced the fuel pump last year, also replaced the pressure regulator. Spark plugs are only a few months old, leads are alright, and the coil packs and module are fine. Its not the IAC or TPS as I swapped them with my folks VY and it still does it. I'm really running out of ideas.

One thing I have noticed is that even with the MACE 12mm manifold insulator, and with the EGR valve disconnected (just for testing this), the plenum chamber still gets quite hot. Could possibly the EGR valve be slighly open all the time? Might this cause idleing problems are there would be to much used air going into the engine?

Any advice would be very much appreciated.

Cheers.

[acarmody]

Is it normal for the IAC to get quite hot? Hot as in you wouldn't hold it in your hand for 10 seconds. Both my IAC and my folks IAC got quite hot after 5 minute drives.

[accentstencil]

It's normal for anything on the engine to get hot.

[acarmody]

I would of thought the insulator protects the plenum from most of the heat. And I would of thought that due to the fact I'm off the throttle half the time the air flowing past the IAC would of cooled it.