I have a 2005 4.0 mustang with an automatic transmission. It was recently serviced with a special oil (cant think of the right word) that lengthens the life and is supposed to make it shift smoother. However (from first to second gear especially) it doesn't shift until around 3500 rpm even if I am just cruising light on the gas. When you pin it it will bounce on the rev limiter for a full second or two before second. It gets better the higher the gear. When its in shift mode and I go from 1st to 2nd when drag racing to get it to shift you have to shift a couple seconds before it is time. For some reason it is lagging on shifting. mainly 1st to 2nd and 2nd to 3rd. Only thing I can think of is the computer might need to be retuned. Anybody have any idea what this could be?