I have an 01 mustang v6 it idles great no problem at all. When you get out on the road and get above 1500 rpm it spits and sputters and hesitates really bad. I had it hooked to a computer and no engine codes at all. The check engine light does not come on and the fuel filter has been replaced. I am really stumped on this one could someone give me an idea of where to start checking?