Slow/fluctuating acceleration?

2002 Pontiac Grand Am, 3400 V6. Aside from basic maintenance and a blown head gasket 60,000 miles ago the car has been great. In the past 6 months though, the car has felt very sluggish, below 2,000 RPMs, 2,000-3,000 RPMs uneven acceleration kind of comes and goes i.e. slow between 2,200-2,300 then a slight burst 2,300-2,500 then slow again with consistent gas pedal application. 3000-4000 pulls like it used to and consistent. 4,000 and above very slow but consistent, can be floored but RPMs are slow to rise.

It always starts immediately, idles fine, and still accelerates normal between 3-4,000 RPMs so unlikely fuel related. Same argument for a potential transmission issue, its perfect between 3,000-4,000 where it's making the most power so you would think that's where it would slip if that was the problem. Also checked vacuum at idle and at 3,500 RPMs in park and it doesn't seem to indicate a clogged cat or vacuum leak.

-1-year-old primary o2 sensor
-Checked and cleaned throttle body
-Ran few cans of fuel system cleaner though it
-New air filter
-Checked fuel pressure ~55psi at all RPMs in park
-Replaced the MAF
-Replaced spark plugs - the old ones had 100,000 on them. looked fine but one cylinder did have some light deposits vs nothing on the others
- New TPS - Old one that came off was very loose where it attaches to the throttle body.

I guess the only thing that has not been replaced is the IAC or EGR. Would those affect only certain RPM ranges though? No codes. Happens all the time hot or cold engine. Happens in all gears but most noticeable in 2nd.

Got the issue on video. You can hear the uneven engine sounds and surges are much more obvious at end of the video near 3,000 RPMs. I am maintaining a constant ~50% throttle up a hill. https://www.youtube.com/watch?v=cCxymyszTH4

Any advice would be appreciated.