Have an 80, SAME THING ! Went through it all, new gas lines, tanks, stoppers, rerouted lines, changed service stations,(gas), oil, moved ig. module, richen it up. I mean there was nothing I/we did not do, I was ready to put it in the lake.
Then after EVERYONE said it was not the ignition, My Hobby Shop Guru, and master of all, said, lets' just try a net ignition. PROBLEM SOLVED !!! The ignition box had a bad solder joint, when the plane bumped something it jarred the wire on the cirucuit board, engine stopped.
Been flying it for three months now with no problems.