Mitsubishi Repair: 97 eclipse revs to 4000RPM, fuel pressure regulator, vacuum hoses

Question
97 Eclipse, 2.0DOHC non-turbo, 5 speed, when car starts it revs to 4000 RPM and won't return to idle. when I drove the car last (when problem started) it surged between 2500 and 3500RPM while moving with it sitting still it revs to 4K. I've replaced the:MAP sensor, both coolant temp switches/sensors, idle control valve, and ohmed the TPS sensor and now I'm scratching my head. My next move is to try and replace the PCM. Thanks

Answer
Rog,
If you haven't checked already, be sure your throttle body assembly is functioning properly.  If the butterfly valve is stuck open or not moving properly, it can cause revving problems.  Also check all your vacuum hoses to the throttle body and fuel pressure regulator as well.
Good luck!