A while back I did some research here and corrected a few problems with my 98 4.2L. After replacing the MAF my truck runs more smoothly. It no longer stalls as I brake to a stop or turn corners. However, I just read the new codes and am dealing with the following: p0141, p0156, p0161, p0171, p0174. Running lean Bank 1 and 2. The O2 Sensor Heater circuts are for Bank 2 Sensor 1 and Bank 2 sensor 2. I replaced the upline O2 Sensors about 2 months ago just before I replaced the MAF. I still have a bit of a rough idle and it sounds like the lifters want to rattle time to time when pulling uphill after the truck is nice and warm. My normal daily round trip is about 10 miles at about 35 mph. And I don't know if makes a differance but apparently I have one of the Canadian built engines according to the Engine Number. Any ideas would be greatly appreciated.