Hi, new Commando owner here in VT I just sold my 78 Bronco and was looking to replace it when I came across this 68 Commando The picture looks better than it is, someone did not do a very good job on the paint. I bought knowing it wasn't running correctly and discovered the #4 plug to be soaked. I replaced plugs, swapped wires, checked timing checked compression---150 across the board. The cylinder has fire. All other plugs are fine. The carb has been rebuilt. I then thought the cam lobe for the exhaust may be worn. I checked the rocker movement with the adjoining cylinders and they seemed the same. I am stumped. I have heard of 1 exhaust manifold in my life being plugged in 1 cylinder causing a skip. My other question is this the original engine? It seems the heads have some air ports blocked off that were used for air injection and the heads have GM cast in them?