When I start it up the RPMs jump up to 5000 to 6000 and back down to under a 1000 and will usually die. If it does not die it is a real low rough idle. When I try to drive the vehicle it will gradually accelerate until I reach about 45 mphs. without pressing accelerator and start surging. when I come to a stop it surges. I have replaced Intake manifold gasket, Mass air flow sensor, fuel regulator, throttle position sensor and pcv valve.