hey man, i had the same problem with my 05 gt. it was doin the skip and hucky buck at around 4500+ with around 18000 miles on it. believe it or not the plugs were going south. I had the dealership change them, after that i had no problems since. I called my tuner about the plugs and he said that because of the design of the plugs they wear out quicker and they should be changed every 12 to 15 thousand miles.