I have 2002 f150 5.4 When I started up in the morning my engine shakes real bad until it gets warmed up then it runs perfect, my engine light is on i checked and tell me that "Cylinder 3 misfire", any help

 

First thing I would be 'suspectiing' is a leaking fuel injector that floods the cylinder after shut-down and clears after start-up from running.
Easy to swap with another cylinder to see if the problem follows.
Check oil for the smell of gas before you start a cold engine to see if this might show.

 

no smell of gas

 

Second thing, is there any coolant leaking from a hose in the area?
Third, change the boot and plug. Be sure to use dielectric grease at the plug to boot insulator.

 

I just started my engine and I could smell the gas inside. after 2 min engine start working fine then start shake again, this is