Craftsman M105 Push Mower runs rough

[CliffG]

I have a Craftsman M105 push mower that is hard to start but when it does start it runs rough and white smoke is coming out of the muffler. It will run rough for a while then eventually it will run normal. I have already replaced the spark plug, checked the oil level, and put gas treatment in it. Today I run the gas out and put fresh gas in and it is still hard to start. Last year it run fine and would start every time on the first pull as it was advertised when I purchased it. I know next to nothing about small engines, but want to try to fix it myself. Any advice on the potential cause of described behavior is appreciated.

Thanks,
Cliff

 

[Rivets]

Please post the model and serial numbers for the engine.

 

[CliffG]

Thanks for the reply, I let it run through the new gas and it finally straightened itself out. It's back to working like it's supposed to!