Apologies if this is a known/easy problem - I couldn't readily see anything relevant...

I've got a 1.4 TDI Greenline, done 40K (in a year :()

I'm getting intermittent power loss in third gear while cruising at ~2000rpm (i.e. ~40mph). Doesn't appear at any other speed or gear, so I'm guessing not a clutch issue? Happens very briefly, and then the power's back on - perhaps the best description is like the clutch being dropped in and out.

No extra noise/smell from the engine I can discern, and no surge in revs (perhaps not happening for long enough) - could it be the turbo, gearbox, or is the clutch shagged?

Thanks for any ideas/advice.

Power loss at a specific torque sounds like a boost issue or possibly hesitation due to a faulty EGR valve or vacuum pipe. Code scan for fault codes would be the 1st thing to try.

Try unplugging the MAF and see if the fault goes away, if it does, the MAF is goosed.

Totally agree with Moggy. I'd get it checked at the dealer if you are not sure what to do. Should be easy to trace and fix.