My 1993 volvo 940 turbo with an automatic transmission will start and run fine. It will run and drive in reverse. When it is placed in drive it will stall immediately. It will restart after two or three trys and run fine again until it is placed in drive at which time it will stall again like the key was turned off. Leading up to this problem, the car would cut out for a fraction of a second when you hit a bump in the road. What is my problem?