When it gets hot enough to start it's dying thing, it appears to miss several times and then the RPM falls so low that it can't recover and then dies. It always starts right back up. It may do it's thing right away and sometimes it will restart and continue to run fine for a few minutes before it does it again. I have thought about buying one of those lighted spark plug wires, that lets you see the spark, to verify what is happening, but haven't yet.
According to Onan, this model of 2500 does not have a low oil level shut down. The model specific wiring diagrams support this. I have changed the oil but that didn't make a difference.
I took apart every connection and coated with "Stabilant 22A" which is an electrical connection enhancement (Google it. It really does work) but it did not help. That is another reason that I am leaning towards the controller and not a poor connection issue.
Thanks for the replies and ideas. I know we will figure this out.
Bob