Don't sweat it. My kids are now 6 and 7, and I think my son (the 6 year old) did not feed himslef fully (i.e. all the time) until 4. He was slow on everything, and now is reading and doing math quicker than my 7 year old daughter did in Kindergarten, so be patient. If getting him to eat the food is more important right now, then keep feeding him until the time of the matter frustrates you, then have him do it himself.