b5 1.8 20v turbo HELP

[drifter.p]

I tried to do my own airbox mod
I removed the airbox and drilled about 10 holes of 25mm in the front of the lower half
And removed the baffle section inside
Also plumbed some cold air pipes from the bumper to the front of the airbox
Since then on start up the engine revs are not smooth
Jumping from 1000 to about 400rpm and back again about 4 times then settle at 700rpm
Once moving it feels better mid range but pull up to a junction and it stalls
But restarts no problem
So out came the gaff tape and covered the holes to see if it made a difference but no change
Also exhaust fumes smell really rich and blip the throttle a little puff of black smoke

Any ideas?