Hi folks, happy new year to all.

I have noticed a problem on my 2000 A4 1.9 tdi (ABJ) since the recent cold weather.
The power output from the engine is very flat - slow acceleration and no pull up hills. Also the Brakes have become heavier - like a lack of brake servo assistance. I guessed it would be a vacuum issue, had a look around the pipes and there is nothing obvious wrong.
I removed the pipe into the top of the turbo and there is some suction (though not a huge amount), on that at idle. Turbo is working as I could hear it spin up when pipe was re-attached. Also same story at the brake servo, some vacuum but not a whole lot.

Does anyone have any suggestions? I am not sure what the vacumm should be like at idle, just a light pull on the finger tip is what I had.

Any suggestions?