I got a diesel D50, it pops when under WOT and has a hard start and ruff idle any suggestions?

 

Well, diesels only need air, fuel, and compression so I wouldn't think it's anything electrical. Could be a vacuum leak, or maybe it's sucking air at a fuel line somewhere.

 

I would first think injectors. Run a can of Seafoam thru it with a full tank of fuel. Run the full tank thru before adding any more fuel. Don't try to clean them all at once like on a trip. The longer the tank lasts the better it cleans.

 

the engine just got rebuilt has about 20miles on it has no leaks when it starts it blows a huge cloud of grayish white smoke then smokes a lite blue. I know the rings are not full seated due to being so fresh but it will run smooth the ruff then smooth again

 

I have quite a bit of experience with diesels generally but I have never worked on a D50 diesel so I need additional info to try to help you. Just rebuilt is a pretty significant piece of info to have originally left out. What engine model do you have? Is yours turbo charged? Does yours use injectors or an injection pump with nozzles? What year is it?