Car Information:
Ford F150
Year: 1994
Engine Size: 5.8L
Trans: Automatic

Issue / Question:
My car is high idle, I changed the IAC valve three times. Last time, I scraped and vacuumed out the carbon. Each time it runs great for 2-3 days then the idle revs up really high. I turn the truck off, wait just a minute and then turn it back on and it runs fine for a few minutes then idles high again.

Answer:
It sounds like the ISC is trying to compensate for an intermittent vacuum leak. It’s possible the EGR valve was sticking open from carbon.

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Magic Mechanic
1432 Lee Road OrlandoFL32804 USA 
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