Iams is mostly corn (which dogs can't process) I would visit the above site for some great recommendations for foods. You want to look for a food that is mostly meat as dogs are carnivores. Personally I feed my dogs a raw diet and they absolutely thrive on it.
I had been feeding my chi jackson purina until i joined this forum and learned it wasn't very good for him. I asked questions on here and if you have a tractor supply near by i would go with 4health or taste of the wild brands. I just switched jackson over to 4health and he has been doing great! He loves the flavor too!