I recently purdhased a 98Z28 from a used car lot.It has an automatic tranny. The tranny seems to maybe skip a gear during acceleration. This does not happen all the time.a couple times it seemed to ease into another gear instead of a crisp shift.The tranny doesn't seem to be slipping and the fluid is clean and doesn't smell burned.the car has 90,000 miles. Do these trannys normally do this ? If so what can i do about it? I know nothing about cars. This does not happen in reverse. Thank you.