2002 jetta 1.8 running rough

I'd say the gauge isn't accurate but fuel pressure may have well been low and it read 0 instead of say 14 psi , Nothing will run at 0 psi . The problem may be the regulator or filter , check for good power/ground connections

As mentioned, your gauge is likely broken or not properly set up. "Nothing runs at 0 PSI" I had a 98 Jetta, it had 2 fuel pumps from factory, 1 in the tank and one inside the right fender... 2 Filters one in the tank one in the rail... try the filters and the regulator first, they would cost much less in parts and labor. Regards