Most likely not. Look for any vacuum leaks first. If all ok, I would look at the iac motor. It may be bad.
August, 8, 2012 AT 1:00 AM
Where exactly could I look for leaks sorry im not good with engines. Is it in the intake?
August, 8, 2012 AT 1:11 AM
Yes, along the intake manifold. You may need some help if you are not familiar with this operation
August, 8, 2012 AT 1:14 AM
What would replacing the throttle position do?
August, 8, 2012 AT 1:37 AM
First check to see if the A/C is cycling as fast as the speed variation, if it is only doing it in conjunction with the A/C on I doubt that it will be a faulty IAC.
August, 8, 2012 AT 6:52 PM
This also hapen when u or I turn off my engine of 2002 f150 and turn on like hour later rpm needle goes up and down like for a 4 minutes look s like normal because I take the truck to cervise they never find enithing in my opinion this us nothing to worry about hope this help
August, 17, 2012 AT 2:31 PM
Sounds like the throttle body sensor, Under normal conditions when the engine is running each time the air conditioning kicks on there will be a drop in idle speed. This is caused by the extra strain on the engine. When the compressor shuts off then it should be normal. As far as the reving up, have found that the position sensor can make the truck do that.
August, 18, 2012 AT 6:08 PM
So it isn't the throttle position sensor than? Or could it be the vacuum that's dirty because when I trurn the ac on and the Rpm goes up and Down. Then I step on it on park or neutral the truck dies.