The problem was that I do not drive the motor home very often — it may sit for several months without being driven, consequently, the gasahol ages in the tank.
I am lead to believe that ethanol begins to break down — “emulsify” in 6 weeks or so. It breaks down into water, alcohol and gasoline. And, the octane decreases.
So, the fuel pickup is alternately picking up water, alcohol and “old” gasoline — causing intermittant rough running and loss of power, particularly when trying to accelerate or pull a hill.
The fix was a new fuel filter, 1 oz of Sta-Bil blue per 5 gallons of fuel and several tanks of premium gasahol. After the engine smoothed out, I resumed using 87 octane gasahol without incident.
FResh ethanol is apparently OK for a few weeks. If you routinely refuel every couple of weeks, you will be OK without Sta-Bil.
One other factoid — in the days of “real” gas, you could resurrect old gas by pumping FResh gas into the tank.
Mixing old, emulsified gasahol with FResh gasahol makes a whole tank of bad gasahol!
If I were a lawyer, I’d file suit to force the government to allow unleaded gasoline back on the market!
I am a believer in Sta-Bil blue!
You make a good point about ethanol not being stable for long periods in unused vehicles. This is also an issue in farm machinery that is only used for a few weeks a year and for military vehicles left idle for long periods.
Ethanol producers and the Department of Defense are looking at the problem.
Until the issue is solved, if it ever is, sounds like your Sta-Bil Blue is a good answer to the problem.
Back before ethanol came along, we used alcohol based Heet to help clean out water and dirt from fuel tanks and systems.