Freelander 1 Freelander td4 misfire

I have a misfire on my 03 td4 at 2000rpm. Just had it back from garage after fitting a new fuel pressure sensor in the HP pump at a cost of £350. It now misfires at 2000rpm and plenty of blue smoke, but when driving it's not bad. It's fine over 2000 or under. Garage said injector 4 was leaking a little but wouldn't cause any problems as of yet. Anyone have any ideas ? Thanks.

after fitting a new fuel pressure sensor
This should be nothing to do with blue smoke as it is fuel related which could only be black or white smoke.

I have a misfire on my 03 td4 at 2000rpm.
1) check turbo for leaks
2) check common rail pressure sensor is mechanically and electrically in good working order, a quick test is to disconnect it whilst the engine is running and see if the misfire disappears WARNING by doing this the engine management light will illuminate and will have to be reset using specialist equipment that could cost you £40