1.9 tdi won't rev, smoke, stalls

[Tangles553]

Hi all, please check all the dot points!

Per the title... I have a 2007 1.9L TDI Golf, BKC engine. It won't rev, if i hit the pedal it runs rough and will eventually stall out. It behaves like it's starved for air or fuel but as below I've done all the troubleshooting and everything seems fine. I'm stumped, please help! See videos below and note the engine bay smoke is from the exhaust, which was disconnected at the turbo.

For the first 20-30 seconds after cold start, it runs fine, boosts, drives normal - then like a switch was flicked, I get the below issue.

• hooked up VCDS - no codes

Checked fuel system:

• drained tank and filled with fresh diesel
• checked in-tank lift pump is working fine, it is, I used the pump to drain the tank
• checked pump primes with key-on (and checked that it does indeed flow out from the fuel filter)
• replaced fuel filter
• checked fuel lines have no leaks or splits
• have rebuilt the tandem pump, which showed no signs of wear or issues
• replaced fuel filter housing after finding an issue with it - fuel now flows correctly to tandem pump

Checked engine:

• checked 'intake flap' is open while engine running - it is
• checked EGR operates correctly, it does
• MAF reading seems normal, no difference at all with it disconnected
• Cam angle sensor reading normal - RPM is correct
• Crank angle sensor reading normal - RPM correct
• injector deviations all within spec
• checked exhaust not blocked - still happens with it removed at dump pipe
• checked turbo OK - have stripped and reassembled, no signs of wear (it's brand new) - still wouldn't explain the issue with it not revving even if the seals were shot
• checked for vac leaks - hard to check but I'm certain there isn't one
• checked and re-set engine timing - possibly need to do again with the proper tools but I'm reasonably sure it's not the issue as it runs fine for 20-30 sec
• inspected rockers and cam lobes - look fine, no signs of wear (new cylinder head)

I'm almost at the point of replacing injectors, there's not much else I can think of

Some videos of the issue. In both videos I'm planting the accelerator pedal and as you can see it won't rev. The second one highlights the smoke from the exhaust really well

VID 20200721 155744 - YouTube
VID 20200718 145837 - YouTube

Piccie of the beast for your enjoyment....