ok, my GF's 91 convertable automatic n/a rx7 can shift into reverse but seems like putting it into nutral. and i dont think it shifts into 3rd either. and when crusin i let off the gas and it goes down to idel while crusin. when i give it gas the rpm just go up really high and smoke is coming out the rear. I cant find the problem and the fluid is full.

 

not very fimilar with automatic trans but it's prossibly shot