1992 BMW 525i auto transmission

I have a problem with the auto-trans neutralizing when u want to kick back on a steep hill or accelerate around any corner it will neutalize, otherwise car runs great, been on long trips, and if u are carefull on the throttle on a steep hill or corner, u would'nt know theres a problem, had it at auto trans shop, they replaced the two sensors in the box and serviced it, still the same, box has done about 145,000km when problem started, was not my car then, and they were told the box is on the way out, car was always serviced and still looks like it just came off showroom floor, my query is could the computer be at fault, or is that about the life of an auto trans box for this model, appreciate any help. Thankyou