I would check your fuel filter and maybe even change it. Also check your primer ball when the unit starts to act up and see if it is flat. If that is the case you have a piched line or your screen in your fuel tank is plugged. And one more thing that we have had alot of problems with lately is gas in the diesel, they will still run, but they will run pretty rough. On the smoking and the hard start, I would check your glow plugs, make sure that you are preheating atleast 30 sec when it is colder out, otherwise check and see if your glow plugs are still good. Good luck