I have a 2000 4.6, automatic, after normal driving of 30 minutes or so, when accelerating from a stop, the tranny will shift through all the gears one right after another before even reaching 15 to 20 miles per hour. Ending up in overdrive. I went inside a store for an hour, and drove home and it was shifting fine. I normally drive short distances but it seems this happens after extended driving. It is a saleen s-281, so the computer has been flashed, and I think the shift points might have been tweaked. I don't know if this could have anything to do with the problem. Any help would be appreciated. Thanks.