Hi, I have a 2005 Ford Ranger 4.0 V6 2wd Edge, with around 175,000 miles. It runs great, however the RPM’s are slow to return and it seems to idle a little high for longer than you would expect when starting the engine. For example, exiting off the freeway with the clutch depressed, the RPM’s will drop from approximately 2300, pause at 1800 for a second, then drop and pause at 1100 for a few seconds before returning to idle. If stationary and rev the engine, they seem to drop back normally.
So far I have changed the IAC valve and checked for vacuum leaks (not sure how exhaustive a check it was but sprayed every joint I could find). My mechanic agrees that it is abnormal, but has suggested that we wait for it to worsen enough to throw a code rather than spend a lot of time and money replacing things that may not be a problem. Also the throttle cable appears to be functioning normally and not sticking.
Anyway, I would appreciate any thoughts or opinions.