Have 1996 Silverado. Had it scanned codes cam e out bad Maf and bad oxygen sensor. Replaced Maf still rough idle and slow response when push gas pedal down. Also no pick up. Replaced all plugs,wires,cap, and rotor. Today performed compression check and all cylinders registerd around 210 lbs. When I removed the plugs, remember these are new plugs, the 1,3,5 cylinders seem to have gas on them and you could smell it. Also can smell gas in exhaust and hear backfire in cat. Could the oxygen sensor on the side with 1,3,5 cylinders be bad causing a rich condition . Does each o sensor control a different bank. There are four sensors all together. one in front of cat and after cat think they are post heated and don't think they would cause this. Do you think its they o sensor on the side with the 1,3,5 cylnders. Also battery is a little weak but don't think it would only effect one bank of cyllinders. Please,please, help.