Wondering if anyone can help...

I bought a Focus tdci 110 on a 56 plate, and ever since I have had it, it has been underpowered.

Have checked pipes, turbo seems ok, the blades aren't loose.

The problem is if I put my foot down about halfway the car wont rev past 3,ooo revs. If i put my foot to the floor it will rev to 3,000 revs, struggle a bit, kick out loads of smoke (colourless but stinks) and then will rev past 3,000 revs.

Anyone any ideas?