I need help my first 6.0

I have a 2003 f350 4x4 6.0 Powerstroke just bought don’t know much about it if i don’t let the temp gauge hit halfway it’ll barely get over 20mph it shakes and feels like there is no power doesn’t matter how hard I hit the gas pedal over 50mph It shakes and bucks like crazy no smoke no check engine light nothing to work from please help if it’s cold and I press on the gas hard enough I get a cloud of white blue smoke no overheating and it idles great