So after a short trip to Graves Custom Muffler in Waco we found the popping in the exhaust...
The baffle was so badly broken that it was beating its way out of the muffler. So for now I had them install a used muffler that they had removed from another vehicle just to get me down the road. I have a set of 40 series flow masters but I want to get her dropped before installing the new exhaust to make sure there are no clearance issues later.
She doesn't sound pissed off anymore. Just a nice clean exhaust sound!
Right now I am currently sitting in Des Moines, IA working. I will be home in about 10 days and then I can get back on her again. Hoping to get the drop stuff ordered while I am here so I can get it installed when I get home.
Oh and I found that the truck doesn't like running on the passenger side tank. I have to look more deeply into that when I get home but I am thinking that since the tank and sending unit were the originals I might just spend the money and put a new tank and sender in on that side to match the drivers side setup and to eliminate those as possible suspects.