I have a 98 gt 4.6l. I have a momentary tick, hick up at any speed, What ever you want to call it.. There are no codes. Took it to a shop and he found no codes in the computer. He put it on all his testing equipment and found nothing. There is no pattern as to when it happens. It seems to maybe have started after an oil change at one of those oil changers shop, but not real sure. However we discovered that I was down a qt. of oil.I think they shorted me. The engineer is in really great shape. It has a factory rebuilt engineer with about 40k on it,. The smog check showed it was running like a new car. I don't drive it alot, only weekends.. Mechanic replaced a couple small sensors that had to do with sending information from the crank to the computer. We where just guessing at that point. It is just a split second hesitation. Does anyone have this problem? Any ideas would be appreciated.