when car gets up to 55mph it stops getting gas for like 3 seconds then picks back up?

I know with my 2001 Ford WIndstar when we would drive it, it would slow down and and spped back up too. We had it check and fixed by a mechanic and they said that we were running on 3 cylinders (we usually runs on a 6 cylinder). I do not if this is what is wrong with your car or not, but see if you can go to a mechanic and see if they can find out what is wrong. Good Luck ;)