First check for a vacuum leak from one of the hoses and/or intake manifold (gasket). Then check for dirty/sticking throttle. These are the easiest things to check so you do those first. Also, the reason the rpms fall when you engage the clutch: you're putting a load on the engine. It's design to do that.
But you're definitely idling too high. If no vacuum leak, scan computer.
Tuesday, December 28th, 2010 AT 2:24 PM