hello new here got a 99 5,9 no mods to engine last few dats when i start motor cold goes romp romp romp white smoke smoothes out no problem tell next morning runs good starts great but fuel mileage kinda sucks need help thanks.

 

How cold is it where you're at? Do you know what your fuel pressure is? White smoke usually means lack of fuel or head gasket leak. A little whiteish gray smoke is normal on a cold morning especially if you don't plug your truck in. Fuel mileage will also be lower when its cold out until the engine is up to operating temp and due to winterized fuel. How far do you drive to work and does it heat up to 190?

 

How good are your batteries?