transmission problem on 1990 Acura Integra

Actually is an old 1987 Integra with only 135,000 miles, driving the gears slips goes back to neutral then I stop the car for 1 minute starts it then it drives but looses gear again after 10 seconds of driving. The fluid is full. Its an automatic. thanks.

Asked by for the 1990 Acura Integra
Unfortunately it sounds like a serious internal transmission problem.