It could be as simple as a sticky valve. Fred do you own stock in rebuild parts or something? Your every advice is to spend thousands on a rebuild.
IMO, take off the head (in the truck) clean it up with a new gasket and maybe a valve job and see how it runs.
So far my original stovebolts have all been excellent runners. Eventhough I also have received the advice you better rebuild more than once. But, it wasn't necessary. I think both my current stovebolts will run another 50 years.
