Changing starter

I went for a good long-ish drive today. I have the MSD Start and Step set at -15 degrees. Cold start is no issues...2-3 pumps, fires right up. So then I cruise 15 miles or so, putt, putt into store parking lot. Come out 5 min later and it's real hard starting. It's like the MSD gizmo really doesn't do anything. I'm leaning towards a FBO bushing and going back to a weighted distributor.

Just for FYI: I did my cruise with no hood....temps stayed around 175.