1986 Fiero GT transmission acceleration

[InTitusville]

I just picked up a 1986 Fiero GT automatic with just over 35,000 miles that has been sitting for 6 or 7 years. I was able to start is up no problem after charging the battery and I can drive it but it's slow to accelerate in drive but I can spin the wheels in reverse. I think because of the age and because it hasn't been driven for so many years it may just be the transmission filter. Any ideas?

The brakes are also spongy and I think it's because the master cylinder seals are bad from time and the Florida heat.

 

[melsg5]

you didnt change all the fluids, engine oil, transmission fluid and filter, differential, coolant, etc. before driving it after it sat for 6 to 7 years?
what do you mean by slow to accelerate in drive?
are you saying the engine revs to high rpms and the car doesnt move ?

 

[Zimgxp]

Reverse is a lower gear than 1st gear is.