Today was about 32F in the morning, engine was shaking pretty bad. After warm up it ran perfect. P0300 code.
Any ideas why when cold? thanks.

 

An guessing you might have an intermittent vacuum leak and once the car warms up it is not present. Wouldn't surprise me if it happens again and the code would refer you to a specific cylinder(s). Maybe worn plugs on possibly the intake gaskets might need to be replaced. Also, check the Big Three vacuum leak causes (IMT o-rings, brake booster valve, PCV hose) just to make sure.