tabo817,
sounds like to me your baby is overtired. They need about 13 hours of sleep per day. He probably still needs 2 naps, say 45mins in the morning, 1hr in the afternoon, then 11 hours at night.
If he only take 1 nap, then he needs about 11-12 hours per night, 2 hours in the afternoon.
To get him to nap better, make sure you let him sleep more at night, say an earlier bedtime.