I have a good question for a problem that persist with my 2000 Chevy Silverado with a 4.8L v8 and 4L60e.
When I apply heavier throttle to get on a highway for example, my acceleration is very sluggish, even all the way to the floor. The rpms build up very slowly and it seems like my transmission doesn't want to kick down to a lower gear when under a load. It will sometimes respond, but not very often. During normal driving, my truck goes through gears just fine and drives normally. Its usually when more throttle is applied. My truck will start up fine and idle perfectly. I've replaced my fuel filter and cleaned out my Mass Air Flow sensor, and checked the trans fluid which is fine.
There is a Service Engine Soon light that shows up which said that there is a problem with the catalytic converter. My thoughts were maybe my cat converter is clogged causing this lack of power? I'm honestly not sure. It did fail emissions. If it is I might give lacquer thinner a shot from your video.
I have a video link posted below of my acceleration. Let me know what you think is.