1999 ford explorer cold idle problem

I have a 1999 Explorer sport 4.0 SOHC. When it is cold outside (below 50 degrees)and the car sat overnight or sat for several hours it wouldn't idle worth a darn, would rev up real high then sputter then
idle high again, and it would die . It would do this for about 3 or 4 minutes then would idle great. The check engine light was on codes said bank 1 bank 2 fuel too lean. We changed the following IAC, O2 sensors, egr valve, air filter, spark plugs,mass air sensor,fuel filter. We changed the o-rings(gasket) on the intake and it FIXED the problem. The o-rings are rubber(like a thick rubberband) and when the motor is cold the the rings were hard and it caused a vaccuum leak, and when the motor warmed up they loosed back up. You can purchase these o-rings from the dealer you will need both top and bottom gaskets bottom rings run about $11 or $12, and the top gasket is $7 or $8.
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I wonder if this is the probem with the idle lately on my 89 Mustang 5.0. I'm having the same problem.
Fred

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Hi group
Found the problem. I took off the hose from the air cleaner to the throttle body and found the throttle plate very dirty. After a thorough cleaning the idle went way up. This was probably from me fooling with the base idle screw over the years. Then I cleaned the idle air bypass valve (also very dirty but not stuck). Finally I reset the base idle and TPS voltage. Now the motor purrs like a kitten!.
Fred

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You think thats why the sticker states " IDLE NOT ADJUSTABLE"
If you have problems its something else, esp. with newer cars They trip a CEL when you fart :-)
Engine (idle) problems and no "CEL" is usually dirt related.
IAC, injectors, MAF or t-body dirty
Or combination

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