91 Century idle problem

My daughter's boyriend has a 91 Century 3100 (I think) with a very high idle speed. He took it to a friend of his who's a "mechanic". The friend said his diagnostic equipment (???) couldn't find anything
wrong, but he should get it fixed before the motor is ruined. The friend suggested Precision Tune.
Onitting the comments about this "mechanic", does anyone have any hints on what the problem could be?
The idle speed is very high & sucks gas like crazy. I haven't driven the car, so I don't have much more than that to go on.
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What RPM is it idling at? Is it all the time or just when it starts up?
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On Mon, 10 May 2004 15:21:53 -0500, "Phillip Schmid"

It's mostly all the time, although sometimes it slows down a bit. I'm really not sure what the rpm would be. I haven't been around when it happens. A thought I just had...... the boyfriend says it "roars" when driving sometimes too - transmission slipping? I'm going to have to see the car for myself; he's not very car literate & may be describing a different problem altogether. Maybe this evening.
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Sometimes a problem does not show up on diagnostic equpiment. A mechanic who says, yes their is a problem, yet I suggest you take it else where is being hounest.
The car could have broken vaccume lines, bad injector o rings, a leaking fuel pressure regulator (filling the intake with fuel at low throttle), a bad IAC (Idle Air Control) Soliniod, a bad TPS (Throttle Posistion Sensor, or blocked off vaccume ports in the trottle body. It could even have broken vaccume lines. Or possible an injector that is running rich. Charles
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Sounds like a vacuum leak to me. Spray around the intake with water while it is running untill it slows down. Also try blocking off any vacuum lines first. Does the heater\a\c controls work OK? Do the vents switch to defrost when you accelerate?

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