Wonder if he ever got it fixed?
Doubt carbon tracking on new plugs and wires.....
Did he use A/C Delco plugs? Good wires? Good Coil?
Basically, you use a spark tester and check output at the end of #1 and #4 wires....if ok, and used a good plug(OEM), could be the injector......another possibility is a head gasket leak, usually at #1 cylinder....is he losing coolant or overheating?