Hi everyone, I have a 1997 2 wheel drive Dakota with the 3.9 Magnum. About 2 weeks ago after the ride to work, I put my truck into park and it was revving at about 1600 RPM's. Never did this before ever. I shut it off and restarted it and it was idling at about 1100 RPM's and after about 12 seconds it jumped to 1600 again. No Check engine light on. I scanned it and it came up with no codes. Fuel mileage has gotten even worse than it has ever been. I have to ride the brake to drive under 30 mph. Changed plugs,wires,cap,rotor,map,iac,tps,iat, completely removed throttle plate and diasassembled and cleaned completely, spray carb carb cleaner looking for leaks...none, swapped throttle plate with normal idling 3.9, no difference. Engine temp normal, running in closed loop, and O2 sensors working good according to scanner. Help!! What is left? 183,000 miles, No smoke in the exhaust, and runs great but that high idle won't go away. I even removed the factory "do not tamper with" idle set screw cover and turned it all the way out. Does not use any oil, I feel like it's an engine management,electrical issue. Please help!! -Daniel

 

check your throttle cable and all the plates. I had a problem years ago with a ford topaz and a high idle had to swap out the throttle body. also my truck seems to do this high idle thing as well usually when I am parked and slowly give it gas it gets confused and raises the idle all by itself. I can shut it off and restart and it's fine. all but the rough idle I'm about ready to swap out the PCM