yes dave, gets warm and wants to park, can go crank it any time there is no want to go on the road,, if a trip out is planned she will flood out a couple times to delay leaving and then start the every 20-30 mile break thing.
Not sure what all modifications have been done so if something does not apply, then ignore it.
A) Stock fuel line from mechanical fuel pump to carb could be clogged allowing fuel to heat up and vaporize. Lays up against front and top of engine.
B) Stock fuel lines run from tanks to carb on inside of frame rail. While there is some heat shielding the lines can clog with rust with age. These restrictions make it easier for the fuel to heat up and vaporize the fuel.
C) The ignition module and ballast resistor (located on plate at rear of engine above bell housing) can be heat sensitve. I have seen them heat up and fail with odball symptoms.
D) If carburator has has not been rebuilt in several years then it most likely needs rebuilding. Not unusual for a motorhome to sit unused a lot. The gas turns to varnish plugging up the small passages inside.
E) Old cracked vacuum hoses can cause the engine to run lean.
F) Vacuum diaphrams on carburator attachments and the distributor do fail resulting in poor performance (Vacuum leaks).
G) Centrifugal advance and Vacuum advance mechanisms in Mopar electronic distibutors are known to get gummed up and sticky with age. This impacts both performance and economy. The pictures that go with this Mopar distributor rebulid article are accessed across the top but they are there. It covers both points and electronic distributors:
The Lost Art of... | Hemmings Motor News
My thought pattern is working on age related issues that take time to evolve. Afterall, it is 30 years old.