I haven't been on the forum for a while and I have been bad and haven't taken care of my RV for about as long. My wife and I haven't used it for about 5 years and I use to go out and start it every ot...
I have no scientific basis for my suggestion but I will tell you what I would try first if it was my coach. Instead of filling the gas tank I would put in 5 to 10 gallons of fresh gas with a pint of SeaFoam. Add the recommended amount of Seafoam to the oil and when the 10 gallons of gas is almost all gone, change the gas filter, oil and oil filter. Good Luck.