Concerning the code "make sure your throttle is at its lowest setting when starting". As for the stuttering have you ever advanced the timing on the injector pump? It may need it there have been many 5530 owners whom have had to do this, me being one of these owners. It fixed the problem with the shuddering and puffing out smoke. Before messing w/ the timing be sure the air, and fuel filters are clean and that you are getting good flow to the fuel filter.
Good luck.