Ok so i am lost as to where to go with this.

I against my better judgement purchased a Focus 2002 LR 2.0ltr zetec without getting it checked out completely.

As i drove it home doing 100ks on freeway it all of a sudden lost power and would not restart. Now the seller told me she had this issue but on the test drive it did not happen, and her mechanic put it down to overheating, So over the last 2 months i have replaced the Cat converter, leadss, plugs, oxysensors, coil pack, fuel pump and thermostat. and of course i am still getting the same problem. When its getting up to operating temp its fine but after about 20mins of driving all of a sudden it bogs down and loses power it sounds like it was missfiring hence the reason i changed to coill pack. Anyone had this problem i can not justify spending anther cent on this lemon of a car but i have gone too far into it just give up.

thanks in advance all.

Who was the dill that told you to change all those parts except the fuel pump, obviously not a mechanic. Why didn't you get it scanned for some information, like a failing crank sensor it would at least give you the heads up at where to start looking.

Yeah that was the first thing i did got it scanned and it come up with nothing.

Find an auto electrician and tell him about your problem, it may be common with them, if you leave the car with them and leave it running when it gets red hot it might stop, and he should be able to find whether it is a spark problem or fuel.