I have a 1998 K1500 5.7 that has a rough idle. Looking at data from a OBD2 code reader it is missing on #7 cylinder. It does not do it while driving only at idle. The truck has had the MPFI to the CSFI. The CEL is not on. You can feel the misfire and the exhaust is rich smelling of fuel. I changed to plugs, wires, cap and rotor on it thinking they may be an issue, no change. I have checked the CMP position and it is around 9.6 @ 1,200 RPM . If I adjust it to get it down to the 2 to -2 range then it misfires on #4 and #7 cylinder. I am thinking possibly the distributor gear is worn causing the issue. Any input is appreciated. Thanks.