Fixed it: since removing ASV plunger, the valve was in the closed position. Secured it open, then drove 200 miles home.
In addition to spraying turbo with Easy-Off, I adjusted actuator rod to make it longer. I think this is mainly responsible for my findings below.
I always plug MAF back in after a new fix. At first, no change.
I tinkered with EGR values at red lights. Was 33768, reverted to stock: 32768, and car compensated with 10-20% power increase. Could almost keep up with traffic.
Suddenly I could go 25mph up the hill, and then I could do 30 up the next one. Then I started "milking" the car.
What this means is to be extremely gentle with the throttle. I had VCDS open watching requested vs actual MAF and boost levels.
The issue is, the harder I press on the throttle, the less power the car gives. When gently cruising at 20mph, and requested MAF is ~400, for example, the actual value will be right on. But if you press the throttle too fast, a huge fissure opens. Requested MAF shoots to 850, and actual MAF nosedives to 220-250. The car loses all power, and boost values match MAF values.
BUT
If you're cruising at 20, with 400 on both, and very slowly press the throttle, requested MAF goes to 480, and the actual MAF does too! And boost follows suit!
Every time I "milked" the car, it got better. Suddenly I was feeling mild bits of genuine acceleration, and I was pushing MAF values into the 500s and boost levels in the 1500s.
I call it "milking" because I imagine it like a cow: if you're nice, sweet, and gentle to the cow, it yields lots of milk. But if you start squeezing too hard, the milk dries up.
I had to coax it for power repeatedly. The car would offer a slight morsel of boost, then I would press slightly too hard and be punished. When I lost boost, I would have to 'find the groove' again. Sometimes, it would be as easy as 0% throttle, then gently increasing until "the wave came". Other times, I would have to rush over to the shoulder because I went to 0% throttle and tried 5-10 times with no luck.
I'm driving on the highway, seeing MAF values reach mid 600s and actual boost levels match requested at 1950mbar.
Over the course of 3 hours, the car almost reached full potential. The MAF broke 800 once, and I confirmed 2150mbar boost.
But the car still had a mind of its own. One second, I would be blasting up a hill (WV mountains, btw), 80mph, blowing through 90, 95, hitting 100 up hill in 4th gear, with ~60% throttle.
Then, without warning, my sweet boost juice was yanked away, and I'd have to 'find the groove' all over again. Sometimes one 'throttle reset' would do it, other times I would limp on the shoulder for 30 seconds while everyone passed me again. This isn't limp mode reset, I did not cycle the key in-between boost sessions.
Even though I regained intermittent top end power, there is still absolutely zero acceleration down low. The "milking" and "finding the groove" issue is much worse at low speeds. 0-60 is non existent.
It seems completely random. There were times I was maintaining 80mph on flat ground, as steady throttle as possible, and out of nowhere - BAM, all power is lost, and I scramble to the right lane.