I have a 2001 ranger 3.0 with 200k and it has recently started to idle around 1500rpms i have checked out the throttle body and iac and both seem to be working as they should and are clean im not too sure what else to check or what is causing it, also when I unplug the iac the rpm’s drop to around 750 which I read is to check for vacuum leak. It idles pretty normal when I first start it but once I start to drives it just kind of sticks at 1500, it also seems to get a little higher with the air on but it will drop after a few mins