I have a 2000 Z24 2.4L 5 Speed Getrag man. trans. The car idels at about 1600-2000 RPMs. If im going down the road faster than 10 MPH and push the clutch in the RPM's will climb and hold at about 4200RPM and will not go to normal idle til it goes under 10 mph as im coming to a stop. I have changed the Throttle Position Sensor with no improvement. Any Suggestions?

sounds like a vaccum leak

sounds like a vaccum leak
Any idea where to start looking (ie what component?)

You should be able to just hear it. It will sound like a whistle of air. Check especially near the front of the engine.

take a propane torch and turn the gas on a little, an run the gas around the manifold and the intake. if the engine revs up and smooths out then you found the vaccumm leak.

if you don't find a vacuum leak, you can use carb clean to spray to find a leak.. you may need a ecm