I'm having this same problem with my 98 Contour Sport, V6. I had the MAF sensor changed about six months ago and just recently had my O2 sensors changed because I was getting a cel with this problem. Although after driving it for a couple of days the cel light came back on and now I am getting a Po420 code. I get the same sputter/hesitation when I get on the high way, it is only about two or three small jumps and as I pick up speed it goes away. Let me know what you end up doing because maybe it will help me out, I am going to have my MAF cleaned tomorrow.
