Code p0172 rich on bank 1, one mechanic says 02 sensor, another says exhaust camshaft sensor..it does stall and rpm spikes from 600 to 800 then back to 600. On one machine the 02 sensors are within in range and are not on another. Also trying to decide on bully dog or g-force for better performance and fuel economy. I am an old school mechanic. Thank for any help..