Originally Posted by Mike1995
Only thing I can think of right now would be to test the TPS sensor.
I agree. This sounds like a throttle position sensor gone bad. I accidentally created this issue once by installing a new TPS backwards -- and sure enough, it revved almost to the redline, and then shifted when I let up on the throttle.
Since you don't have OBD-II, you can't just plug in a scan tool to read the TPS voltage. If you have a multimeter, try Dan'* TPS test.