Sometimes I hesitate to tell people with new birds what I'm really thinking. I think that maybe they will feel I'm a scare monger, but I'm going to because it's so important for Palmer.
Amazons are prone to being overweight and perch potatoes and that contributes, along with their healthy appetite, to developing problems with their organs especially their liver, kidneys and heart. Just like us people when we are obese and inactive. Fatty liver is very common among Amazons and I believe that one of Clueless' Amazons has a problem with fatty liver. Your bird has been on a bad diet, is 18 years old and is a prime candidate for liver/heart issues. What I'm finally getting around to saying, is make darned sure the vet does and CBC and Chem panel on Palmer and you will know if Palmer is ok or not. Then after you bring him home keep him on a lean (lowfat, low sugar) diet.