2005 Ford Escape is my computer going bad in my car

I have an escape (2005) with 110,000 miles on it. Having multiple issues: 1. Today the OD Off light came on and flashed. Turned the car off then light stayed off, later the care wouldn't shift to a higher gear. Never had any trans issues no rough shifts or anything like that this is all new as of today 3/27 2. Was told by the on board info screen to check the gas cap. Gas cap was on tight and secure. 3. Engine has missfired in cylendar 3. Took it in, diagonis is change wires and plugs. Any thoughts could I be having a catastrophic failure of my transmission and plugs and wires? Help me please