Stutters when accelerating, poor milage and recently soot from exhaust

2006 Jetta TDI
176k

My Jetta is not accelerating smoothly. When accelerating, it hiccups or shutters for a split second causing the vehicle to jerk. Just recently noticed that above my exhaust pipe a soot is building up on my bumper. There is more soot built up underneath the vehicle on the backside of my engine near the right side CB axel.

Needs some help diagnosing the issue. Im about to move across the country and I'll be driving the Jetta and need to fix the issue.

Could be a worn turbo control ring.
Search for "zip tie mod"...

Original camshaft ?
You are not getting enough air in the cylinders . Lots of variables here

The hiccup or shudder could also be an injector going bad, would explain the excess smoke too.

Worn VNT control ring. You need a new turbo. EGR cooler is leaking too.