If it were mine I would move the timing slightly one way and try it. If it makes a big difference, good. If not I would move it a bit the other way.
That is a good suggestion if it was running bad. It starts "right up", runs awhile and quits. Pumping accelerator saves it for awhile? Does not seem to be a timing issue to me.
I won't be sure until he finds the problem. You could be right.
