speech delay

Does anyone have a child that is speech delayed? My 3 year old says words but not speaking in full sentences just yet. Should I have him evaluated? He knows his colors. Know how to say his Abc. Can identify his body parts. Can follow instructions if I tell him to throw something by away in the trash. Also knows his flash cards with the pictures and without He copies off of me if he see me doing something like sweeping he will got get his broom and do it also. It's a lot of things he can do.