I have an 87 4cyl Duke auto which for the most part runs well. Problem is the shifting
1. When it shifting, it is a hard shift from 1st to 2nd
2. 2nd to 3rd is smoother than 1st to 2nd
3. Higher RPMs and the shift is smoother
4. When I open the throttle on her, starts to take higher RPMs before the shift takes place for 1st to 2nd
5. After the open throttle sometimes the 2nd to 3rd gear shift will no longer happen, but is fine after a restart
I already changed the filter and fluid and topped her off properly. Been considering TransTune (from the Seafoam boys) but am thinking it would not affect it. Is there a particular sensor or component I am missing?
'87 Pontiac Fiero - 2.5L Automatic