New wires new plugs new distributor cap and button runing bad and missing

To prevent costly guess work .. This is what's eventually going to have to be done.. Scan test with live data which includes misfiring cylinder identification .. Fuel pressure test including *engine off* leak down to eliminate fuel injection spider problem.. Located under the intake plenum... You can check for excessive distributor shaft lateral movement as that's a pretty common problem on that older 4.3L... IF 'lateral' shaft movement is noticeable, replace distributor assembly..... *Re-check the plug wires for proper firing order.*

most likely the injector if you have already addressed the common tune up type items. There is an updated injector assembly available.