Massey 491 engine trouble

[rhinestoneranch]

My MF 491 is having a hard time running- It has been extremely cold. It will start, but then start missing and belching out dark smoke. I've replaced filters, cleared water out of the filter, and bled the valves but no change. The 491 has a turbo charger.
Any help?

 

[rhinestoneranch]

When the problem initially started, there was approximately 1/3 tank of fuel. There was no visible problem with the fuel. I have since filled the tank with new fuel.