96SLPCAMAROSS

hey guys i have a 04 silverado ext cab 5.3 with the 4l60e tranny and last month i installed a pcm4less custom tune and after i installed it i noticed the shifts felt very weird but i just thought it was because the tune had higher shift points and there was no torque management. so today on the highway i layed into it and caught passing gear about 50mph and the rpms went to 5k then droped down to like 3500 then was slowly trying to climb back up but it seems like it took forever to move.when i drive normal the 1-2-3-od shifts all feel fine even the passing gear under 35mph shifts and feels fine but passing gear after 45mph or so feels very weird even when i manually downshift to 2nd gear it dose the same when i stomp on the gas.i installed my factory pcm back in the truck to see what would happen and it still dose the same.i really hate to take in for service but oh well.let me know what you guys think is wrong.oh and sorry for the bad grammar i suck at paragraphs and sentences

96SLPCAMAROSS

nobody?