Torque converter is a possibility ==i would guess stickey valves in transmission --besides having it rebuilt iwould try this first use a quart of K&W transmision conditioner after it is in== warm the engine up about 10 min enguage parking brake==then cycle the shift through each gear until you feel it enguage then drive it for at least 30 min =stop every few min and cycle through gears == if this works with in a week take it in and have the filter changed on the transmision



