Over the past year or so, my 1999 Ford Ranger would slowly return to idle RPM after removing my foot from the gas pedal. At first, the RPM hang only happened during the hot summer months.
The RPM hang now occurs when the temperature is cold or hot. The car starts and idles around 1000 RPM. As soon as I add throttle and let go, the idle RPM stabilizes around 2300 RPM.
I have replaced the manifold air sensor, PCV valve, the idle air control valve and the throttle position sensor (TPS).
I have an Actron AutoScanner CP9165 device and took a baseline reading of my truck in 2011. I noticed the TPS data is reading higher than it should after I replaced it. The baseline should read 14.5 and the new sensor is reading 17.6. The replaced sensor read 12.5 and I had the same symptoms so I am not certain the TPS sensor was bad.
I have taken off and cleaned the throttle body but it wasn't that dirty. I did notice this morning that when I pushed the throttle body closed, the idle RPM would drop a little but no where close to a standard 1000 idle RPM.
1999 Ford Ranger 3.0L Flex Fuel
