1997 - 2003 Ford F150 General discussion on the Ford 1997 - 2003 F150 truck.

'03 Crew cab 4.6, Engine idle surges

Old 01-11-2016
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Default '03 Crew cab 4.6, Engine idle surges

Truck was running fine and then it started to have low idle and stalling. Code said it was Idle Air Control and replaced it. Now it idles at 1700 -2000 rpm at start-up for about 1-2 minutes. It then the idle drops, but it surges up and down in range of approximately 600-1200 rpm for another 1-3 minutes before it holds steady idle at 700 rpm. Once it is put into gear with the brakes on, it wants to take off like I applied the gas pedal and idle is back up to 1200-1500 rpm, or it starts to surge as if the gas pressed then released repeatedly. The engine drives fine but if I let off of the gas it wants to stay at a higher idle(1600 rpm +/-). Also when at idle, 700 rpm, I turn on the A/C the idle goes up to approx 1200-1600 rpm. It also does so if truck is in gear and coasting at idle speed, turn on the A/C and it accelerates.
I thought it might be the new IAC so I returned it and got another new one, does the same thing. Cleaned the old IAC and put it back on the truck and it still has low idle and stalls.
Can anyone help?
FloGrown is offline  
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