Do you possibly mean P0171?

I don't think the O2 sensors have any part of the starting program. As I recall they don't really have any input until both they and the engine are at regular operating temperature. The leak in your exhaust could be causing the code, but I doubt it is causing the hard starting. I've got some big ol' cracks in my exhaust manifold and have never seen that code, although my CEL is on (always). If you have access to a fuel pressure gauge connect it inline if possible and see if you have good pressure cranking the first time around.
Good luck!