Transmission Problem/idle too high

I have a 95 Buick and when i drive it seems like the transmission don't wanna switch seem like it stuck in first gear. Is my transmission shot or can i do something about the fluid. and when i put my car in park it idles real high how can i adjust the idle to where its normal. When i get a tune up will this resolve my problem with the idle?

Many things can cause a trans not to shift, poor engine performance at the extrememe , vacuum modulator bad or disconnected, internal solenoid issues, these things must be checked out on site by a qualified person. Again high idle can be a number of issues that normal t/u will not correct, a scan will be in order here.

P1640- QDM 1 failure, P1650- QDM 2 failure, P0712- Trans Fluid Temp sensor circuit low input: are the codes i'm getting.