I bought a 1994 Ford Taurus about 2 months ago just to have a cheap car. The dealer told me the transmission had been re-built about 5000 miles before I bought it. Considering the history of these cars, this made me feel better about the purchase. It has about 117,000 miles on it. The car runs very good, and the transmission was great for the first few weeks. Lately it has started to shift strangly while in drive. This typically happens after a short commute. I will drive about 4-5 miles, turn the car off for an hour or so, and when I get back in to go it starts. It acts like it does not know when to shift. It acts like it is in 1st gear at times, and letting off the gas does not seem to help. Occasionly it will even slam hard into the next gear while driving.

Any thoughts?

have you checked the fluid? You may need to add. Jiffy lube will check it for free. I think there is a filter/screen in there somewhere that could get clogged, but I don't know.

If it was just rebuilt, or a rebuilt transmission that was put in, check to see if there is still a warranty on it.