I'd try a good pressure washer, then slosh some carb cleaner around and PW again.....
I'm sure other solvents eat gas, but carb cleaner works very well in small amounts.
Also, like Jason touched on; You'll never get it mounted nice without the rubber mounts. You may get it on there but things will crack in time, best to get some mounts on there and do it right but were all different in our opinions of "right".........
All our government does is distract us while they steal from us, misspend our tax $ and ruin our country