300 tdi running rough and smokey

Looking for a little guidance, I was checking my 1997 disco 300tdi and found a leak on the leak off pipe banjo connector, metal pipe, I got a replacement and connected all the new leak off nozzles only one snapped off when I was tightening it. I thought I might have to take the injector out to get the broke bit out so I removed the pipe on top of injector and removed the clamp nut for the injector which was the second last one at back of engine, but ii didn't remove or try to remove injector as I noticed the broken bit of bolt was slack so I put the injector bolt back on and tightened and refitted pipe on top of injector but after repairing diesel return pipe the engine is just not running right sounds OK on idle but when reved it sounds hasitant and blue smoke from exhaust, surely just removing clamp bolt and diesel pipe from injector hasn't caused injector to fail? Ii does sound like it's not quite firing right on all cylinders as it is a little hesitant, before I fixed the leak off pipe it was fine. Any help greatfully received.

Cheers Twin