Starts fine but rev high

SOURCE: Rev's to high

IF THE THROTTLE SENSOR IS ADJUSTABLE TRY TURNING IT BACK SOME TIMES YOU NEED TO SLOT THE HOLES THAT LOCATE IT TO GET SOME ADJSTMENT

SOURCE: 2002 ls2, starts, engine revs high and then shuts off.

this is a problem within your throttle body assembly.your idle control valve is most likely blocked and your throttle body is dirty.if this is not it another popular saturn l series problem is a leak in the intake manifold.

SOURCE: engine is reving up a lot even when foot is not on

This sounds like a fuel system or ECM problem. It should still be under warranty and I recommend you take this in for Warranty repair.

SOURCE: from cold start my renault megane starts to over reving

Having exactly the same problem with my megane and the mechanic just charged me £687.00 and does not know what to do!!!