I'm still working on the 1998 Ford Ranger XLT 4X4 V6 4.0. It started with when I would come to a stop the idle would occasionally not go down but would stay in the 1200-1500 range but after about 10-30 seconds the idle would go down. I replaced the throttle cable. No change and in fact it got worse. I changed the throttle body and had the idle adjusted at the dealer because they had the right scan tool, no change. I changed the idle air control valve, no change. I changed the throttle position sensor with no change. I even replaced the coolant temperature sensor to the block based on issues other people had. I'm out of ideas. Do you have any ideas or tests I could do to pin point the issue?
Bump.
Have you cleaned your MAF sensor or checked that it is reading correctly? On my '99 3.0, I cleaned the MAF sensor and it wouldn't stay running the first two times I started it afterwards. It relearned itself after a couple minutes of crappy idling and runs great. The MAF should read around 4 grams per second at idle. Old mechanical throttle bodies aren't that complex, the throttle plate rests against a set screw, raising and lowering the screw changes where the throttle plate stops when you take your foot off the gas. If it's not against the screw when you take your foot off the gas, or revv it with the throttle cable under the hood, something's binding it up.
