still surging idle, went through complete list please help

[347lxvert]

i have checked everything in the surging idle checklist, i have a new mass air meter, new ect, new act, fuel pump is new, have cleaned everything i can find that might possibly be dirty, installed an iac spacer, adjusted it out all the way and my car still does not idle, it will idle smooth in park, but when i try to put it in gear it will die, but if i idle it up when putting it in gear, it will idle when it is in gear sometimes, it usually idles better in D, than it does in R for some reason, oh yea, i have new o2 sensors and my iac is only 6 months old. Please help

 

[backfocus]

Have you checked it with a vacum gauge? See what the gauge reads it should be between 17 and 21 hgi. If not you have a vacum leak, which is what it sounds like to me. It is a start anyway.

 

[jrichker]

It sounds like the IAC isn't working. It is supposed to open up and provide more air when the idle speed drops off. I would check and clean the electrical connections, including the black & white 10 pin connectors.

 

[88306stang]

I had a surging problem to. It would get worse when you put it in drive and it ended up being a vacum leak. Replaced the vacum hose and it idled nice and smooth again. I would go through and check all your vacum lines and replace any that dont look good.