Is my Tranny Slipping?

[85t-typebuick]

i dont know if my transmission is slipping or not? i put it in drive and if i sttomp on the pedel it just wines out until i let off the gas then it will shift into 2nd gear? its been doing this for about a year and no change, or not getting worse,,
i forget but somebody told my theres something on top of the tranny that might be bad but i forget?
any help?

 

[SSedan64]

TV/ThrottleValve cable adjusted too tight, TV plunger in valvebody binding/sticking, Governor problem are a few things that can cause late shifts.
What rpm does it shift at when you lift off the throttle?