2.0 TDI Occasional Misfire

[Jockeyblade]

My Golf 2.0 TDI with 140k on the clock has always run well. However, in the last few days it seems to 'misfire' at mid revs. A blast of the throttle seems to clear it.
Thought I might try some Wynn's Xtreme Diesel System Clean which I've seen in Halfords. Is this worth a try? Or have I got a major problem brewing?

[Gazwould]

Injector loom .