I have an 88 200 Horizon. I've used the E10 fuel for about 3 seasons, the main thing is to make sure that the fuel filters are changed regularly. Most of them have a water seperating filter that needs to be changed at least once a season. The thing with ethanol is that it will clean whatever gunk was in the gas tank out of it, which can clog filters. The other issue with E10 is that the ethanol can absorb water and if it absorbs enough the water can seperate out and cause problems. You can remove the cover that is over the gas tank and remove the gas gauge sending unit and look in the tank, if there is water or crud in the bottom you can pump it out or have someone do it for you. BE CAREFUL AROUND GAS TANKS, even static electricity can ignite vapors. Other than some red crud in the bottom of the water seperating filter the first year, I have not had much in the way of ethanol related problems.
1988 Four Winns 200 Horizon 4.3 OMC Cobra 1998 Jeep Grand Cherokee 4.0 Selectrac 2007 Jeep Grand Cherokee 5.7 Hemi Quadradrive II