garskejp

Hey there guys I have a problem with my 92 Ford f150 4.9 and have no idea what to do next. Here's the run down a couple months ago I was at a stop light and the rpms suddenly dropped and got all erratic. From that point on it had trouble idling. I drove it for a couple months after that but it got worse and worse. I was forced to feather the throttle to keep it running. Now here is a list of parts replaced that did nothing for the problem. Fuel pump, fuel filter, distributor, cap and rotor, plugs and wires, throttle position sensor, fuel pressure regulator, EGR solenoid, ECU computer. Im probably even forgetting some. But none of these have helped. The truck starts but you have to continually pump the gas to keep it running. There are moments when it will just purr for a split second then go right back to running horribly. So please if you have any suggestions I would greatly appreciate them. Im at the point that I've put so much into it I refuse to give up now!

R.S.LOGAN

Idle control valve ?

garskejp

I have not replaced that but do you think that could have that much of an effect on it.

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R.S.LOGAN

Does what the name implies .

How an Idle Air Control Valve Works
An IAC (idle air control) motor is designed to adjust the engine idle RPM speed by opening and closing an air bypass passage inside the throttle body. The cars computer or PCM (powertrain control module) receives information from various sensors and will output signals to adjust the idle air control motor in or out to adjust engine idle speed by controlling engine idle air. An idle air control motor can fail one of two ways, either the motor short circuits and stops working or the motor will develop high resistance and cause the idle air control motor to react slowly, either failure can cause the engine to stall at idle. When a trouble code scan is performed it sometimes won't always detect a failed or weak idle air control motor.

Could try cleaning it first , but may need replacing .

FORDF150JUNK

Id check easy dumb things first. Check all your intake tubes and make sure there's no vacuum leaks. Also get some throttle body cleaner and clean it. Sometimes that flange gets gummed up and sticks. If all that fails, then try cleaning the IACV.