I just can't seem to get my fire right. I was starting a fire to cook some ribs and placed my charcoal in a chimney. I filled the whole thing up and waited until they were all greyed over. When I dumped them in my offset box, it seemed the charcoal burned quickly and was hardly there. I'm using Kingsford My temperature rose but then dropped to 211 degrees in just 30 minutes. I need help. What am I doing wrong?