Black smoke - low turbo boost?

I've finally got the car driving and now it's time to make it work properly.

Symptoms:

• Low power, struggles to hold onto 5th gear
• Black smoke, starts up with a good burp but does not struggle. Then black smoke when pulling away and accelerating.

Things I've checked:

• Air lines - All hoses are good
• Turbo - seems to be chucking out extra air when rev'd. (had the 'to intercooler hose' detached and you could feel the difference)

Things I'm not sure about:

• Turbo pressure - squeezing the intercooler hose and then revving the engine seems to give a small pressure increase, but I can still squeeze the hose down.
• Waste gate actuator - stuck a bicycle pump on the small pipe from the turbo and pumped it right up, arm hardly moved! Seems stuck?

Injectors?
Fuel Injector pump diaphragm been played with?
Turbo dying?

What else can I try? Seems to be drinking diesel and just spitting it out in smoke!

Inj pump played with, check to see if all the seals are still there.
Pop diaphragm out and look for the biggest rub mark on the taper, this is the std position, refit this towards the front of the car, if still smoking have a look at the fuel screw, 6 and 13mm spanner, back if off 1/4 turn at a time.
Lots of people dont realise that a turbo wont produce proper meaningful boost until the engine is pulling hard on the road, it will move lots of air when just revved at a standstill but not boost.

What engine? Is air cleaner clear? Apart from a visual check of rotor vanes as lynall says to check turbo you need a boost gauge and load on the engine [steep hill]

It's a 300tdi, air cleaner looks good to me - but I'll swap it out. I'll check the FIP too and see where that's been set.

Will try to get boost gauge. What kind of range do I need? There are no landrover specialist people here - and NO-ONE drives diesels.

300 is 1 bar approx 15psi, boosts starts from approx 1800 rpm upwards.
You know when you are in to high a gear and it takes an age to pick up then really gets into its stride? thats when its boosting good and proper.
Any old gauge will do the trick, easiest way is probably to T into the little plastic pipe that runs from the turbo to the top of the injector pump, I think the rubber hose to the wastgate is a pita to get at on the 300
Dont worry if the gauge jumps about as proper boost gauges have a damper built in to eve out the fluctuations.

sourcing a gauge for the turbo - think I'll get a 1 bar ranged one and do it properly. Would be a good thing to use.

Changed air filter.
Covered hoses and joints with soapy water to try find any leeks. Found a few small ones. all plugged.
found there was no hose from the FIP to the turbo, just holes. sorted now.

Still smoking like a bitch.

Will try diaphragm tonight to check for tampering. Then clean out inter-coooler next.

Bloody thing. Pull up at the lights, pull away and leave a cloud of soot.