My guess is the governor flex ring in the Roosa Master pump. I had a similar experience on a JD 2030 in cold temps. I initially thought it was a gelling problem as it would starve for fuel then quit. Wait a little bit would start right up then do it again. Don't let it go too long I was told that it starts out stalling out but progresses to the point where it will run away until it self destructs. Removal and re installation of the pump takes a little care and understanding also. There are umbrella type seals on the pump shaft that need to be oriented correctly or you will end up with fuel going into the crankcase.

 It is only going to get worse with the newer ultra low sulfur diesel fuels coming on line now. There is less and less lubrication in these fuels for the older rotary injection pumps that need lubricity in the fuel. It's a good idea to add additives or use diesel with bio diesel added to help add some lubrication.

Another govt. mandate touted as not costing us anything. Just like the removal of lead from gasoline was not going to hurt anything either.  Anyone that was still using older gas tractors pretty hard with unleaded gas soon found that hardened valves and seats were not free either and will definitely dispute the "no cost" claim.

Good luck I hope your problem does not get any larger.