Flat spot with smoke?

As I go through the gears, just before I feel and hear the turbo kick in there is a flat spot in the power. If I hold the accelerator in that flat spot she will smoke black.
If I push the accelerator a little more she goes through the flat spot, the turbo hits and there is a puff of black smoke.

I have changed the air and fuel filters and will be cleaning or replacing the intercooler if needs be.

Is this normal?

Thanks.