Hi, I have a 1986 Ford Bronco XLT and for about a month now it has been idling at about 1500-2000 rpms in park and neutral. When I put it in drive, it drops back down normal.

It also has a problem with dying if I stay stopped in drive for too long. If I get stuck behind a train or I just hit a long red light, every once in a while it will start to run pretty rough and then die, but it's unpredictable when it will happen, sometimes it is fine at long lights. It starts right back up but as you can imagine I would be much happier if it didn't die at all.

My truck has a new IAC I put in about 3 weeks ago.

Any ideas on what the problem could be would be great, Thanks.

 

Welcome to FTE and the Big Bronco Forum.

Since you are running EFI, you might do well to run a KOEO and/or KOER (self-diagnostic) test just to see what the on-board computer "thinks" is wrong. This will save you and us from guessing and save you time and money. I say this because there are a handful of things that could be at the root of the issues you are experiencing and there is no point in troubleshooting every potential problem if the self-test can pinpoint the problem first. If you need information on how to administer the KOEO or KOER tests check HERE. Once you have gotten the test results (fault Codes) post the numbers here and we can certainly assist in troubleshooting.