I had the same issue. Try a replacement Carb, one that is already rebuilt. ( Only took me 10 min to remove & replace both carbs) now I have a spare carb to rebuild--After a few adjustments--while running, almost like new.
Stoogeguy, April 2010
I too have this problem, same mower. I think its a bad coil. Now to find one somewhere will be a task I think.