1995 Ford Contour problem. Plz help

I just bought this car ( Ford Contour, 1995)and it is shaking pretty bad when I stop at a stop sign or at a red light. The lady I bought the car from had the same problem in 2002 and that she "had the MLP changed" - it helped, but didn't fix the problem completely. Can somebody help me and tell me what the hell is a MLP and what is to be done with that to fix the shaking problem. Thank you