Hi Tom,welcometomyturbodies. No idea about your problem but thought I'd say hello anyway. Somebody on here will be able to help though.
Some basic things to check: boost leak and camshaft condition. There are articles in the FAQ on how to do this.I don't have an answer for you but I have what seems to be an identical issue with my 06' Jetta Tdi 1.9l. It has 118,000 miles on it and I changed the TB myself at 111,000 miles it's run great up until about a week ago, at first it sounded like a simple exhaust leak but after some invasive investigation that checked out and there was no leak, so I pulled the cover off the air filter and found my noise. I traced it back to where the intercooler air enters the intake on the passengers side of the motor. My schucks orielly OBD2 scan tool shows a DTC" diagnostics trouble shooting code" of PO101 which is mass or volume air flow circuit range/ performance, this is a code that came from the intercooler sensor because of the exhaust coming fromthe intake. I can't solve your problem but maybe we can work together and get something figured out.
I just had a new head installed. I picked it up new from Parts Place for VW for just over $2000. Includes valves, cam, etc. Practically plug and play 3 days later.So I ended up pulling the oil pan and found some metal, so I then pulled the valve cover and an lifters and found that my cam wore a hole in one of my lifters causing it to fail, next I suppose is to pull the head to check valves and pistons ugh, thats a bummer. A new head from vw is $3750. I'll replace the motor if it needs a head
This is a fantastic price given that fact that a cam kit by itself is 600-1100 depending on cam.I just had a new head installed. I picked it up new from Parts Place for VW for just over $2000. Includes valves, cam, etc. Practically plug and play 3 days later.