This is for my 1997 Chevy PU (1500) with a 5.7 engine, 130K miles. I fixed my truck, with Jim's help from this board last Saturday (camshaft Position Sensor) Truck ran fine. Drove to work yesterday and after everything got warmed up, ligght came on again. Code P0172 which says system too rich Bank 1. Ive seen comments in other forums that this could be anything from a MAF sensor to O2 sensor, or maybe the fuel regulator. Any idea what troubleshooting I should do to narrow it down a little?