Right Mag Only Rough Running

Gentlemen thankyou for responding on this.

To bring this full circle I want to let you know what we found that fixed the problem.  We went back and reinspected all of the leads, wires and plugs (Sams suggestion).  The last one inspected was the cause.  We found the bottom Plug socket on #3 cylyinder rubbing and chaffed through on the Coolant tube running along that side, the right side of the engine.  We replaced the socket and now the Engine operates normally on that Mag.  When I pulled the plugs and inspected them I missed this.