Gave the K75 to a non-BMW garage for a service and it has come back a bit "iffy"!
Bike does start, but needs encouragement. Tick over seems OK, but throttle needs nursing until she's got temperature.
Poor acceleration. Black, sooty plugs on all cylinders. Altering TPS on or off makes no difference. There is a clunking from the fuel tank if I rock the bike back and forth with a full tank. I checked the filter was the right way around and re-installed it, but it seemed to have been done right first time.
Its using more fuel than usual, so running rich. All fuel lines are OK: not kinked or squashed.
Tick over is about 1000rpm when warmed up.
Recently re-built water/oil pump which seems to be OK.
Backfires occasionally in 2nd whilst slowing down.

I'm wondering how to approach this one.....
wisdom gratefully received!!

Could the clunking be caused by the fuel pump not being properly located in its clamps? Not sure if that could cause your problems though.
Moral of the story? Do it yourself next time! You will get a lot of satisfaction.

Check the vacuum line from No3 injector body to the fuel pressure regulator if that is leaking or off the mixture will go rich because the vacuum is down and so the stupid computer thinks it needs more fuel. I had a split line once and it caused all sorts of headaches before found it.
If they did a sync on the throttle bodies then they would have pulled it off to get the vac gauges on and may not have put it back.

Yup, I concur with a vacuum leak.

I had a sort of clonk comming from my K75 tank and when I adjusted the float to make the light come on at something resembling the correct piont it stopped so I concluded that the float was knocking on the inside of the tank but that was only a guess.
The filter is also not supported and can move a bit on the rubber lines so it may be worth a check if that is it.

New fuel pressure regulator has solved the problem. There was also a split in the crankcase breather hose. With these repairs the difference has been immense!!

Well done good to see you have fixed the problem.
Regards,
K-BIKE