[JekylandHyde]

Between the turbo and the air filter is a large sensor called the MAF or AFM (mass air flow or air flow meter). When you removed that to install the turbo, did you happen to disconnect it by the 2 little screws on either side of the huge wire?

If so, that was a really terrible mistake.

The proper way to remove the AFM is the incredibly thin, c-clip that surrounds the connection point. You remove that C-clip and then it simply unplugs.

If you unscrewed it, then I am afraid you damaged the unit internally.

That is my first geuss.

My second guess would be a really bad boost/vac leak somewhere in the intake tract.