I had about 35 hours on my Highlander powered by a Rotax 912 when I decided to see how ehe would do when fueled with LL100. After fueling run-up, takeoff and climb were all normal. Upon lowering the nose after level-off, the engine started running roughly and losing power. I reduced power and the engine started to run normally. Thinking I had fuel contamination, I returned to the field,re-checked for water and found none. Upon checking the inline fuel filters, I found a little trash in the right filter.I shut that side down and had an uneventful ride back to Toccoa.
I then drained the tank and filtered the fuel and found no debris. I also checked the carb float bowls and found no debris there, either. I drained all the avgas and loaded up with 93 octane auto GAS,The flight that followed did not exhibit any of the problems of the previous flight. Picked up a load of 100 LL and the same problem popped up.
Any ideas?