Can any of you experts shed some light on why my 58 plate tdci suffers with flat spots. Nearly every time i slow down, change down to 2nd gear (revs dropping) and try to accelerate again theres a flat spot (a delay in picking up again). Naturally this is somewhat worrying as often this happens at junctions when you would normally just accelerate away but instead it doesnt do anything. Ive even put it into 1st gear and after an initial delay it then goes.
On another point i notice that i get heavy smoke when i accelerate.
your help would be greatly appreciated.

Welcome to the world of turbo deseils thats the norm u have to adjust ur driving technique all turbos suffer the same and the smoke is the characteristics of a deseil engine.

Firstly not an expert and I'd wait for some other ideas before taking out your turbo. 

 

Do the turbos have adjusting veins? If so they may stick and not be at the right angle for accelerating but instead for higher speeds. This could also explain the smoke if your turbo is not getting enough air in the cylinders.

Id get some EGR cleaner.

 

I had flat spots accelerating in 1st and 2nd but sprayed some Wynns EGR3 cleaner into the intake and gave it some revs and sooooo much black Shizzle poured out the back.

 

Now it runs better than ever

I agree with Shrek81, turbo lag! Just make sure you're above 1800 rpm if you want to put your foot down after slowing down.

 

Under normal driving you should only notice the smoke at night when another car has its lights behind you, your rear view mirror has tinted and you have stepped on the peddle.

 

If you're under the boost level and you've stepped on the peddle it will smoke until the the turbo catches up with your right foot and in most cases the turbulence behind the car would have cleared the smoke during daylight.

 

It's one give away when a diesel in front of you has stepped on the peddle and there is no boost!