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Erratic idle

1994 Ford Explorer; When I start it, if I don’t step on the gas it will stop. If I give it some gas when I start it, the engine will race and then decelerates about 2000 rpms and keeps doing this, it does get better as the engine warms up. But the idle is really rough. It has new wires, plugs, vacume lines, oil change, air filter and battery. If I put the gas pedal to the rug, it will go from 4000rpm back down to 2000rpm and continue doing this as long as I keep the pedal to the metal. I had it put on an analyzer and it didn’t read anything.


Sounds like a bad idle air control valve

Inexpensive part and easy to replace

What engine do you have?

Let us know if you don’t know what the valve looks like

Thanks for the info. I will give it a try. Thank You. I tried an answer site that charged me $29.99 and I never got an answer! What a rip off. I love this site.


That’s disappointing about the $29.99 down the drain . . .

Anyways, when you replace the IAC valve, don’t forget to replace the gasket

And I also recommend cleaning the throttle body with carb cleaner at the same time

Please let us know when the problem is resolved

I don’t think it is the IAC, not if WOT and it drops to 2000 rpm. I would look a t a fuel delivery issue, either a clogged fuel filter of a bad fuel pump.

Does it dog out on you when you go WOT under load after the engine is warmed up?

Another possibility, the spark plug wires are out of order.

He’s probably bouncing the engine off the rev limiter if he’s flooring the throttle with the transmission in park. I don’t think it’d go back and forth from 2K to 4K, but I’d bet it’ll do at least 3K to 3500.

If all this started after the new plugs and wires were installed, I’ll bet that it is the firing order, especially if the engine is a V8. Most people who are not heavily Ford experienced get this wrong because they follow the firing order as stamped on the engine without knowing one little fact, how Ford numbers the cylinders.

If you know the firing order on a small block Chevy, you can use it on the Ford 302 as long as you use the Chevy’s numbering order.