A loss of power when under load.

I have a 2000 Golf TDI with 279,000 Klms. Occasionally, I loose acceleration when the vehicle is under load. Ex. when going up a hill and want to speed up, the vehicle will occasionally go flat and will not increase speed. I find that when I stop the vehicle and restart the engine, the condition goes away and returns to normal operation. Wondering if anyone might have any idea as to what may be happening.

MAFS

You have an admirable number of kms. How does the beast run apart from this loss of power issue?

pinholes in vacuum lines if not the MAFS.

Runs like a charm. My daily drive to and from work is around 240 klms. Still get my 1000+ klms per tank and rides with comfort.

I had the same problem with my 2002 TDI Jetta with only 35k mi on it at the time. when I would shut it off and restart it it would go away. It would only do it when it was running hard. I didn't get any DTCs on the scanner, so I replaced the fuel and air filters, and changed the oil. I am not sure what it was, but the turbo wastgate works on oil pressure. so if the oil gets to thick, it might not function properly. what type of oil do you run? I run 5\30wt synthetic. The dealer said that it needs the thin oil for the wastegate to function properly. I don't really know what the problem was, but what I did seemed to fix it. It has not done it since. As you said that shutting off and restarting fixes it. It seems you have the same problem as I had. Change all filters and oil. and see what happens, good luck.