Using corn cobs and wood chips is not a good idea. Your iguana may eat these and get an obstruction in the gut. Iguanas are herbivores. If you feed meat or too much protein in the diet, it causes renal failure. When you buy your iguana, have it tested for parasites.
Many iguanas die from parasitism.
When a lizard is sick, it may stop eating, drinking, and moving around. Skin disease and metabolic bone disease are common ailments. One problem owners sometimes encounter is aggressiveness. Male iguanas especially become more aggressive as they get older. Some males will get pretty vicious.