Disco 1 Help - Blue smoke

My project discovery has now done 1500 miles since getting back on the road, recent problem has appeared whilst doing 50 on the motorway I began to notice slight misfire, then whilst going up hill in third gear around 2500 revs I began to loose power dropped down a gear a big cloud of blue smoke followed then back to normal. same thing happened when trying to gain speed on slip road again in third gear. I have changed air filter and crankcase breather. While driving round town no issues but again when putting any load on problem comes back. Any advice would be appreciated has anyone had similar problem (suspect turbo Issue? ) but don't really know where to start from

Were the 1500 miles all fine? You didn't experience the same things at same speeds/conditions?

Just thinking the timing belt might have slipped, might be worth dropping the timing case off and checking tightness of belt and injection pump timing ..

The problem just occurred over last couple of weeks, the timing belt was done in January along with the tensioner, at low speed all appears fine it's only when there is a bit of power required the problems start. Cheers for the reply bit in the dark at the moment

Still not got to the bottom of this issue,now cutting out and misfiring at low speed does this rule out turbo? Have been advised to check the lift pump by working the priming lever found no resistance possible pump problem anyone had similar issue? Pump was changed during rebuild but is a Brit part pump?

Have you checked the fuel lines at the fuel tank? They're prone to cracking at the nylon bend and letting air in .. Similarly check the sedimenter isn't full of jelly and crap. I'd take the fuel lines apart at each end and blow into them with an airline to clear any potential debris. Might be worth trying to syphon fuel out of the tank and seeing if there's crap in the bottom of it, fine silt .. Open the top when you're checking the fuel line fittings and use a syphon pump with clear hose so you can see how clear the fuel is.