Have a 99 Monte Carlo with 3100 engine that has some idle issues. About once a day when started the car will idle around 2000 rpms. If you shut the car off and restart it, it will usually idle @ the desired 700 for the rest of the day. Havent been able to catch it doing it while ive had my scanner yet so havent ben able to watch sensors. Replaced IAC with no luck. This car also has a slight misfire at times. Doesnt do this problem @ all times either. Car will misfire on accleration but once above 2500 rpms will smooth out. This car has had a new fuel pump, pressure regulator, intake manifold gaskets. Have tested for vacuum leaks, no leaks. Sometimes will idle fine @ start but be idleing @ 2000 rpms within 10 miles. Coils have been tested, injectors have been tested. Both problems persisted before and after the repairs completed. Any advice would be appreciated. thanks

With all the other work done and parts replaced, I would suspect a bad TPS.