My 4.6 GT has a hiccup problem. I press down on the gas and after a few seconds it will hiccup. By hiccup I mean a half second hesitation. I changed out the plugs and wires, BUT it is still doing it. The mechanic said that it was suppose to do that and that it is to save gas. I was thinking it was either the injectors, fule filter or fuel line. Any suggestions? Thanks in advance.