99 gtp tranny problem

[BRIAN70SS]

NEW GUY HERE. HAVE A 99 GRAND PRIX GTP. WHEN SHIFTING THE TRANS REVS REAL HIGH(usually about 4000). WHEN YOU LET OFF IT WILL EVENTUALLY SHIFT. WHEN YOU KICK IT DOWN IT BANGS. THIS ONLY HAPPENS AFTER THE CAR WARMS UP. WHAT COULD BE THE PROBLEM.CAR HAS 180,000 THANKS

[FuglyGTP]

check your fluid level. take it to a trans shop and let them do a free diagnosis if that doesnt fix it