Saturn SL2, 2001, 134,000 miles Engine Idle Problem

2001 SATURN
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DBGAUGER
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I'm having engine idle problems. When stopped, car in drive, the engine will rev to about 1500 rpm's then settle back to 800 rpm, usually. Sometimes when I stop and then put it into park it will rev to about 3000 rpm. It seems to also fluctuate while driving

I replaced the Idle Air Control valve and cleaned the EGR valve. No real improvement.

Any suggestions would be appreciated
Nov 8, 2007 at 9:24 AM
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2CARPRO JACK
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Has the check engine light been on? Check for vacuum leaks at the engine. If the light has been on, have it scanned for codes, might give us a place to start
Nov 9, 2007 at 7:54 AM
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DBGAUGER
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No check engine light. I replaced the coolant sensor. The scan is showing that the engine temp was at -40-degrees. Obviously not correct.

Are there two coolant sensors on this engine?
Nov 12, 2007 at 5:44 PM
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2CARPRO JACK
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There is a coolant sensor (PCM) temp sender (gauge) and air intake temp sensor (PCM)

Does it still read -40 ? be sure you replaced the right one, the temp sender and coolant sensor look alot alike on Saturns
Nov 13, 2007 at 7:29 AM
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DBGAUGER
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I replaced both sensors and it's still reading -40. After replacing the sensors it corrected it for a short time. Could it be the computer itself?
Nov 19, 2007 at 9:50 PM
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2CARPRO JACK
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Could be, but first you will need to do a pin to pin resistance check on the wires to be sure they are good to the PCM
Nov 20, 2007 at 7:52 AM