have u tested the glow plugs? we've ran both our 7.3 trucks with 2 dead injectors for a period of time and as long as the glow plugs would come on,(needed a new relay) they would start in even the coldest times of the year. if u dont have any dead holes when warm i would get a full set of injector o rings and throw those in. holding pressure over nite in the hp oil system is important for cold start performance.