Last night I was headed to the local pool hall and bar, and came to a stop light. When I took off from the stop light, somethign wierd happened. It was in 2nd gear, and my foot was steadily on the accelerator, not moving. Suddenly it downshifted, and jerked the truck forward. My foot didn't move, but it acted like I had a manual and intentionally downshifted so I could take off and gun it.

Could this be the TPS going bad, or just a fluke that may only happen once?

 

Automatics do that, just because you put it in second gear, doesn't mean it will stay in 2nd, i don't know for sure with rangers, but i drove an automatic and had it in 1st, i slamed the throttle, and it shifted up to 2nd, and 3rd. I am assuming, your transmission assumed it needed to shift down to supply more power to the wheels, i may be wrong, but try to see if it happens again

 

this was different. I ddin't give it any extra gas for acceleration reasons. I was coasting with my foot on the accelerator just to stay at the speed I was going at. and it downshifted, the rpms went up (duh) and my whole truck jerked forward. and I mean jerked, it wasn't normal.