Ty1er
Newbie
I have a 97 K1500 with the 5.7 vortec, over the course of a month or two I noticed my mpg steadily declining but no performance issues...I replaced the plugs and wires, cap/rotor, took the K&N that the PO off and put factory air box back, replaced MAF, and fuel filter all over the course of a week. Still no improvement on mpg, now I have a misfire on #4, less than 100 miles on plugs and it was fouled so I replaced it. Next day, same thing. Its intermittent and only cuts up at lower rpms(under 2k) and under acceleration, to the point it almost wants to stall. Compression on passenger bank cylinders were all good (138-140 psi), there is a P0300 misfire code, and 02 heater bank 1&2. Fuel pressure at the Schrader valve is 61psi but drops rapidly