Troubleshooting Head Components

Just heard back from the shop. Milling went well and the bare minimum was taken off. Apparently the head wasn't as warped as I had initially thought. He took a good look at the rest of the head and found that the exhaust guides were all in rough shape, which may account for the reason they were burnt to a crisp. He is going to apply new guides for an additional $100. Intake guides were looking great. My question, to follow up with my previous post, is this: what would cause the exhaust to burn so hot? Am I not getting enough cool air in there to alleviate the problem which evidently caused a bigger problem later? I do live in Southeast Texas where our summers regularly peak 109 on the heat index, but I rarely drive it during the day to cut back on the consequences of extreme heat. What can I do to help the exhaust temp? Thanks in advance.