transmission problem
 

97 camry 4cyl....when you accelerate normally the trans stays at 3k until hitting about 45mph then drops only if you lift slightly on gas, then rpm drops, it used to drop sooner under normal not fast/heavy acceration. any ideas, oh, car has 160k on it and trans fluid changed around 145k and does not smell burnt. should i flush trans or just change fluid and what else could it be??????????