Issues On Throttle

[therealtrikky]

Ok, I'm hoping for some insight from some more experienced SC folks! I bought a 1992 SC400 with 212,000 miles for a "steal". As it turns out, the timing belt was installed incorrectly. I fixed the issue, put the motor back together. The car idles great, has a very small off idle hesitation when you press the pedal, and is otherwise smooth throughout the rpm range. HOWEVER, once it warms up a bit. If you press the pedal, it will rev to approx 3K rpms. then act as if you let off the throttle, drops to approx 1k rpms, then back up to 2,500-3k rpms, and back down to 1k. 3rd time around however, it will rev to near redline with no issues... I plan on checking fuel pressure and the mass air flow tomm. Has anyone else come across this? I know this car has several additional sensors/components. Any feedback will be greatly appreciated! Thanks again for taking all the time to read!!