I have been reading to try and figure out my own 2002 jetta 1.8T issues and I came across your post where you asked the person this, "A couple things to notice while you're driving... Do you ever see the CEL flashing? Does your car get poor fuel mileage? Does it seem like it lacks power, or stumbles when you try to accelerate from a stop?"
The codes for my jetta are P0301, P0302, P0304 and p1601. The car definitely stumbles sometimes when you first start the car in the morning and then accelerate. I haven't noticed any difference in gas, but the CEL flashed once before.
I was just wondering your thoughts? Thanks