1999 Quest high idle in gear

3.3L 134,000 miles. When put in gear, idle increases by 4-500 rpm’s. NO engine codes. Nothing seems to be sticking. Tried cleaning throttle body – does not make a difference. Checked vacuum OK. Idle speed will not go down no matter what I do. Dealer tells me they have not heard of this. Has anyone seen anything like this? Can anybody tell me what to look for or what to try next? :confused:

Look for a vacuum leak. Check the EGR system. Idle increases when putting in gear is puzzling. Also make sure IAC is working properly. Let us know if you find a leak or not.

Look for a vacuum leak. Check the EGR system. Idle increases when putting in gear is puzzling. Also make sure IAC is working properly. Let us know if you find a leak or not.

Thank you! Kept checking for vacuum leak but couldn’t find it. Saturday we removed the plenum. Our son found the culprit! The PCV hose had a hairline split on the side of it, near the clamp, located where you could not even see it with a mirror -- we know, we looked! It is a formed hose, so we will order a new one from the dealer today and we’ll put it back together this weekend with our son’s help. What a relief to know the source of the problem. Thank you for your help! :wink: