1997 buick custom stumble on acceleration

my 1997 buick custom stumbles on normal acceleration then goes away, no codes, it is a drivabilty problem hooked up a snapon mt2500 scanner, still have no idea why, sometime if you stop the pedal when it stumbles it will slowly accelrate like it should. I've cleaned the egr, made it not as bad pvc was bad replaced that ,and that helped a little,bit it still stumble a bite, any more ideas will help.

Do you have any codes pending or stored? What does the TPS signal look like on the scan tool? Do the readings rise and fall smoothly as the pedal is depressed/released or does it jump around or have any flat spots?