I changed the filter and ATF in my 3.8 Sable tranny at 88,000 miles. Around 104,000 miles I discovered the tanny was leaking fluid. So, I tightened up the pan bolts and the leaking stopped. I added ATF to the proper level. However later on I noticed that the tranny wasn't down-shifting when I came to a stop. Instead it stayed in a higher gear which caused the engine to stall when I came to a stop. I can drive it fine by starting off in 1st gear, then manually shift to second gear and finally manually shifting to Drive. But to stop at a red light, I have to manually slip into neutral.

I thought a fluid and filter change would help solve the problem. So I removed the pan, fluid and filter, cleaned the pan, installed a new filter, re-installed the gasket and pan, and added ATF to the proper level. I did not pressure clean the line from the radiator as a short time ago I had replaced the radiator. The pan had a fair amount of dark fluid in the bottom of the pan near the magnet.

I've still got the same problem with the tranny not down-shifting as I come to a stop. Any suggestions?