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Hello All, I have a 99 S.D. with a 6.8 V10 in her. Just lately I have noticed when driving after warmed up if I am on the highway or in some traffic that when I am driving and I get off the freeway and pull up to a red light she wants to idle around 14 - 1500 rpm. If I give the throttle a quik tap it settles down. I checked and replace the filter and also cleaned the throttle body thoroughly but it didn't make a difference. I was hoping some of you out there may have some suggestions as to what to look at next as it has never done this before and I don't want to go replacing a bunch of unnecessary things if I don't have to. Any suggestions would be appreciated. Thanks
This almost sounds like your TPS may be starting to go out, I would back probe it to see if it's within the .53 to 1.27 volts, if not then it would probably be time to replace it. That's just my guess though. If you do change it, it would probably be a good idea to clean your throttle body out too.
Clean the MAF and IAC (idle air control) sensor as well. A wrong reading MAF will really only rear its head at idle. If you have a scanner look at how much air it’s pulling while acting up and compare it to a known good. If the IAC is on its way out it’ll act the same as described letting too much air and causing a high idle. You could also check fuel trims to see if it is a vacuum leak (IAC) or an adjusted measure (MAF)