Hi all.

I'm facing a reocurring problem. I have a 2000 VW Golf Mk4 with the 1.9 TDI AHF engine (110hp), back in Decemeber it wouldn't start althought it would crank all day long. With the help of a tow truck driver we got it started by giving power from the battery to the valve that allows fuel into to the diesel pump. I took it to a trustworthy shop that's done work for me in the past but there were no codes or anything coming up, car sat for 1 week but the problem never happened again. 

This week the same issue happened and got it started the same way by giving power to the valve. I took it to the shop and and they changed the valve but also said that they found some issues with the wiring going to that valve that they fixed and should no longer be a problem. Also they mentioned they had suspicions of the immobiliser being an issue but wasn't trippng any codes again.

When I picked up the car on thursday and noticed a significant decrease in power, almost as if the turbo wasn't working, however I could hear it when revving the engine, decided I'd wait a day or two and get a chance to take it on a highway where I could reach higher speeds instead of 25-30mph city and see if it's any different however on Friday afternoon same problem happened and wouldn't start, I managed to jump it again with power to the valve but it was too late to take it to the shop. And when I did take it on the highway I noticed again that the power difference is significant and was almost struggling to get out of its own way.

Is it some weird coincidence and the turbo might've gone bad or perhaps it's that new valve and wiring they allegedly fixed or could it be something else entirely as I don't know what to look for 

Attaching a link to a picture of said valve - https://imgur.com/VYoHZmD