Whoever you talk to at suburban must be new or was not a technician I have worked on RV furnaces for over 30 years it’s normal for them to cycle on and off I’ve never seen one that didn’t you can continue to work on this thing and let it drive you nuts and I’m telling you it will continue to cycle on and off for the rest of its life once you check the flow and the pressure of the regulator and clean the oil out of the lines which only usually is in the line from the tank to the regulator and sometimes in the low pressure line but it rarely gets into the appliances as they are always above The main gas line fluid does not run uphill yeah less the line is completely full which I doubt would ever occur