P0131 is for your front O2 sensor on the driver's side. It and P0171 are related. I'd hop under the truck to make sure that the sensor is connected properly and the wires are not crimped or anything like that. If everything looks fine there, then the problem is that you are in fact running very lean on the driver's side. What mods have you done recently?I did the relearn today and I went and cleared my codes. I thought I would just be clearing the P0300 again but I had some other codes:
P0171: Engine running lean
P0131: 02 sensor malfunctioning
I don't have any cats so that explains the P0131 code but I never had either of those codes until after the tranny swap. I checked all of the connections today and the Wait4me tune was supposed to automatically delete those 02 codes. Before the relearn, the engine sputtered and idled around 4-500 rpms, now it idles better at around 6-700rpms, it cuts out still though. What should I do to find out whats wrong?