2002 Dakota Sport Quad Cab 4.7 4x4 Automatic 170,000 Miles.
Recently had a P0171 code and very high and erratic rpm at idle. 1500 rpm
I replaced the upstream O2 sensor. The code went away. Since then the idle is still high at start up (1000rpm) and it has a hard start when cold.
I tried your vacuum test with a cigar. No leaks detected.
Could this be the fuel pump going out? I have read they are known to fail.
Thanks for all you do, great videos.
Check your Idle Control Valve, clean the throttle out and MAF sensor, then see what happens. Scotty has a great video on this. I did it to my '99 Ranger last summer and it was so gunked up it wouldn't start and run for a few cranks, haha. It relearned itself in a few minutes. A failing fuel pump would have issues putting enough gas to the engine to maintain the high idle. Too much air to fuel on a cold engine will cause problems with a cold engine, they need more fuel than air to start.
