ive had the same vibration for the last 2 years that ive owned my 92 celica (5sfe). Ive tried so hard to find out what the problem is but still have not. So if you find out, let me know
. As far as you transmission, it sounds like its not kicking into overdrive, thats why it stays at 2800rpms and doesnt kick down to 2400rpms. My transmissions sticks a little like that when i first start it up, it wont kick into overdrive until i driveit around for a few minutes. Ive had the transmission fluid and filter changed but it didnt do any thing...i may just have the whole thing flushed out. Hope this helps.