Why does my 2000 contour jerk?

I just bought a 2000 ford contour with 109,000 miles on it. A week after i bought it, the car started jumping and jerking really bad. And when i say jumping i mean hard jumping, my head almost hits the steerin wheel when it does this. I have paid alot of attention of when it does i and it seems to do it most when the engine is hot. Once it starts dong it it will do it at all speeds. it goes on for about 10 minuted and then it stops and goes back to normal. Also when its happen the overdrive off light blinks. it seems that when the overdrive light is blinking the car doesnt jerk anymore but once the light turns back off it starts acting up again. i just recently got a tranny flush which didnt really change anything. Pls help me

VSS or MLPS sensor.

Thanks for the reply.
I am not ruling out the VSS but I dont think that would only do it once the motor warms up. Now what is the MLPS?
Just looking for a heads up incase I do in fact need a new trans. What am I looking at for a rebuilt trans R/R? Or a used one installed? pricewise
Thanks again:)

Thanks for the reply.
I am not ruling out the VSS but I dont think that would only do it once the motor warms up. Now what is the MLPS?
Just looking for a heads up incase I do in fact need a new trans. What am I looking at for a rebuilt trans R/R? Or a used one installed? pricewise
Thanks again:)

Manual Lever Position Sensor.