OP said, "One saw is a Stihl 025 that I know has had problems for many years. The owner took it to a shop at least a couple of times, it would run okay for a while and then start having problems again. I tried to use it recently, it seemed to cut okay, but the longer I ran it, the less it would idle."
Just ran into this problem two days ago with a Stihl 025 that had good compression and a good spark. I found a new 025 carb in my supplies and installed it. The saw's engine then started on the third pull and ran flawlessly. Tune up I gave it was minimal. Problem solved.