Was recently getting flat spots at ~3k rpm when giving it the beans. Fault codes came up for cam timing and crank shaft sensor. Did some digging around to see this pointed at a failing crank angle sensor (engine speed sensor). Didn't want to wait til it failed completely and prevented starting to set about replacing.
Priced it up with TPS, recall it was like £100+, so shopped about and found it at Euro for £60! Genuine bosch unit, with the VW part number kinda rubbed off (?).
All the guides say to do it from underneath, but I knew better (

) and decided it could be done from on top. I guess if I'd gone to the trouble of putting it up on stands would have taken the same time and might have saved a few raw knuckles but got the job done from over the top. Couldn't see what I was doing, felt around and undid something that felt like the sensor. Kinda relieved when I had pulled the right thing out!

Now runs like a treat and seems to have got some va-va-voom back.