Engine wont stay running off start, unless i push down the accelerator? Any place else i may have overlooked? No engine light on either. Also.. where would i find the IAC on a 3800 series 3? Thanks.

I drive a Buick Lacrosse 2005

I don't think the series 3 has an IAC as it is completely fly by wire.

thanks alot, i kind of thought so because i couldnt find anything anywhere lol! What do you suppose may be creating this problem?

Check for carbon fouling around the butterfly plate.

Yup what Mike said ^^^^^^^ . . . and/or goo or buildup etc.

Thanka guys. Just finished cleaning it, was gunked right up with carb buildup. Couldnt imagine how hard the poor butterfly plate was working. Now it starts no problem without the accelerator pedal. Also idles nicely.

Cool! Thanks for letting us help out!

Not so much that it was working hard, but the carbon buildup was blocking the airflow. The butterfly opens up just a tad bit to allow some air flow. And these butterflies are stronger than you think.