1994 Isuzu Rodeo Question Idle speed rises and falls.

1994 ISUZU RODEO
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P_DIFFY
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Engine Performance problem
1994 Isuzu Rodeo Question 6 cyl Two Wheel Drive Manual 121 K miles

Idle speed will go as high as 2400 rpm then slowly return to near- normal. Did this before but cured its self in time. This time came on shortly after spraying intake with cleaner. Replaced IAC valve and throttle position sensor from wrecking yard but only improved for short time.
Havent found any serious vacuum leaks.
Jan 26, 2009 at 6:47 PM
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JACOBANDNICKOLAS
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Hi:
It sounds like you hit the items that I would have recommended. Since you got them from a salvage yard, I wonder if they are good. You may want to have them checked. Also, is the check engine light on?

Joe
Jan 26, 2009 at 9:00 PM
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P_DIFFY
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You asked if the "check engine light" is on. No, and when I checked for codes I got a 12. Looks like this means all is well. ECM ? Wiring ?
Jan 27, 2009 at 10:48 AM
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JACOBANDNICKOLAS
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The only thing I can say is to check main wiring harnesses going to the ecm to make sure they are tight and clean.
Jan 27, 2009 at 11:37 AM