WARM STALLING ISSUE

You might have a failing Idle Air Contorl Valve, IACV.
It keeps the idle steady when engine load changes and I am sure they get a good workout in a motorhome.
The other possibilities are carbon depositis and sludge buildup. You can make sure your fuel filter is changed, if applicable externally, and that you run a can or two of quality fuel system cleaner. BG44K is about all I will recommend as there is nothing else that works as well. Two cans will clean a motor and fuel system right up. During this time period the engine may behave stragnely as deposits are removed and passades get temporarily blocked or cleaned out and deposits make their way to the oil pan or out the exhaust. It is a good idea to change your oil one tank after the last can of BG44K, which will be one can per tank so the third tank of gas you will see improvement and your oil will get dirty from all the deposits removed.
You could also have other issues if this does not solve the problem. I think since it is intermitant and on warm up this is the right place to start. If issues still persist I am going to give you a walk through diagnostic for engine stalling situations. When it talks about pulling codes, your vehicle is an OBD 1. This means it is not always as easy as hooking up a reader. However Advance Auto ro Auto Zone will do it for free if it is something that can be adapted which is often the case. Then if you need electrical components tested or tools for testing, they also will test components for free and they loan out specialty and test tool kits.
Just use the link below;

http://www.2carpros.com/articles/engine-stalls