connection to ecbm problem?no start,replaced allparts...common problem in astro?

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p0300 random misfire, occurred before and then after I replaced wires,cap,rotor,plugs, coil. replaced fuel pump in there also. now its doing same thing again. it occurred after rain. its dry now. can start it,runs rough. no ac. was told to check wireing to computer..dude said the wire is rouuted along driverside frame and could have broken wire causing problem.?I haave done about all I know of. Last week it ran excellent..now not so much. cannot trust it, which sucks. Anyone hear of this problem before?