Hello,
I have a 97 ranger XTL with 311780 miles on it and I am having problems with the idle. when I first start it up it runs up and down dose not want to settle down until it gets warm. I have replaced several of the componets including all the emission control sensors, Throttle position sensor, mass airflow sensor, IAC Valve, EGR, EGR Vacuum regulator sensor, PCV Valve, carbon canistor valves and all vacuum hoses as well, new coil and wires, spark plugs, air flow sensor and it is still doing it. I need help could someone give me a few idea's on what they think it could be please it is driving me crazy.

 

Check for vacuum leak.

sounds like unaccounted air is slipping into the motor.

with replacing loads of parts its likely air is getting in some how, time to cigar test it

 

I had this problem awhile ago, and my issue was a blown thermostat (it was a fail-safe thermostat, so it causes it to be stuck open) and this causes the engine to take longer to warm up, causing idle problems until the temperature gauge went to the middle (normal range). I don't know if this helps, but its either this or a vacuum leak

 

03 ranger 4.0, ive replaced everything possible, including the motor for to the death rattle, long story. any how, I had a hanging idle, sometimes slow to return to normal, bad gas mileage and poor performance, I thought I was pulling a trailer a times, a slight hill would turn into a mountain. let my expensive endeavor of throwing parts become your benefit. go to the salvage yard and get a throttle body with the TPS still attached, clean it and install, problem solved. salvage yard will run you 45-60$, New 300$. my power is back, idle returns quickly and idles smooth.. good luck