I will start using E5 and hopefully that will get it under.I failed on high revs. Put two bottles of engine cleaner through and put half a tank of the new Maxol E5 fuel that is 5% organic ethanol the night before the test. No problems the second time round. It is an old car so I also put some oil specifically for old cars in. I used Redex fuel cleaner. I also drove it in very high revs for a few days beforehand.