2000 Ford Contour Bucking missing possible transmission?

Engine Performance problem
2000 Ford Contour 4 cyl Front Wheel Drive Automatic

I have a 2000 Ford Contour. 4 cyl. About a month ago it started to miss and buck like a horse. Then the speedometer and other guages acted up and lost power. Found out the alternator was bad. Replaced that but still got the bucking and it seems like it goes into neutral (or like the clutch is depressed at times - it is an automatic). I pulled the wires and found oil around all of the plugs so I thought I had found the problem. Replaced the wires, plugs and new valve cover gasket. Made no difference. The coil checks out Ok and even tried another. I had the transmission fluid changed and again nothing different. I had a transmission guy drive the vehicle and he hooked up a testing unit that gave a reading of a TRS (Transmission Range Sensor) as a possible cause. Since this is a non returnable item, do you think this could be the problem?