New member here with a couple of questions. I have a completely stock 94 GT, runs perfect, no missing, stalling, etc. It has 75,000 miles on it if that helps. I have CEL coming on after about 3 or 4 miles of driving. I tested for codes and came up with 172 which is 02 sensor showing lean bank 1. I went ahead and bought sensor but I'm still getting code. I also bought the MAF spray and cleaned it as best I could. I was talking to the mechanic at work and he said low fuel pressure and/or a vacuum leak could cause this as well. I changed the fuel filter hoping that was it, but code still comes back. Could fuel pressure be culprit, I guess what I'm asking is, if it was pressure it seems like I would get a code for the other side as well, so I was thinking it had to be something else, or is it possible to have low fuel pressure only on 1 side?? I haven't started to check for vacuum leaks yet, is there a problem area I should try first regarding the vacuum? Any other advice for what could cause this, thanks.