I replaced the original automatic transmission in this car with a used one a year ago. I now have about 20,000 miles on the transmission and it seems to be slipping in first gear after the car has sat for 8 hours or so. When I put it in gear it seems sluggish whether going forward or back. If I leave it on the incline of my driveway overnight, start the car in the morning, then try to drive up the incline the car feels like it could slip backwards down the incline until I give it enough gas to go forward. My 240's and other 940 don't act like this. This slipping only occurs for the first 30 seconds or so after starting. After that it seems to work ok. Shifts are all solid. I've flushed it with 12 quarts of Castrol synthetic dextron ATF and that seemed to help a little. Is this problem serious enough to leave me stranded somewhere? Will it fail suddenly or continue to get worse before failure? Any suggestions to remedy problem? Thanks for the help.
Marlin