Volkswagen Repair: 96 VW Jetta engine problem, vw jetta, fuel mileage

Question
I have a 96 Jetta Trek 2.0 with 134k miles that is running rough. The fuel mileage is down considerably, but it does run.  When I checked the spark plugs, one plug was covered in black soot. The other 3 were quite clean.  Do you have any ideas?
Rob

Answer
Rob,
I know very little about these newer VWs but if that one plug is black, I'd start looking at that cylinder's injector. It could be burnt oil deposits also but I doubt it with the fuel consumption problem. There's a slight possibility that that cylinder's plug wire is bad and not allowing the full spark to reach the plug. Try going to www.shoptalkforums.com to see if they might know. Thanks!