1999 Mercury Station Wagon weird shifting

My car has started shifting in and out of overdrive when traveling at highway speeds with the cruise control on and off. Car will also shift funny now around town. The speedometer also starts to bounce all over the place when it starts to do this. Trans fluid is now burnt and was replaced at 89000 miles. Car now has 120000.

There is an electrical plug just below the master brake cylinder that I pulled off and did notice trans fluid in it before when it did it the first time. Cleaned it out with electrical cleaner and dried it and it worked fine until yesterday. Checked the same plug again and there was no oil in it this time.

Used a OBD II and did not get any codes.