Continental A75 power loss, BIG Mystery

[Tasca]

This weekend I've made more test...
adjust idle mixture and the engine runs smooth now and solve carbon on plugs that had on previous flight and got 2480 rpm ! great !!
The Strombergh I've has no mixture control, it is NA-S3-B
I'm using 100ll avgas with very good quality control, I’m in flying in a air park and something like 65 airplanes get same fuel and nobody is having problem.
I'm the only operator of the Cub and I fill the plane. My PA14-ET use the same fuel and there is no problem.
In this 8 months trouble the tank has been suppled at least 8 times.
There is 2 different arrangement for carbs:
1. venturi 1-1/4 main #49 bleed air #65 (already test) this combination was flying
2. venturi 1-1/4 main #50 bleed air#65
3. venturi 1-5/16 main #46 bleed air #60 (already test)

what may had happen to the engine reduce the gas eating ?? it has only 225 flying hours

This weekend I've made more test...
adjust idle mixture and the engine runs smooth now and solve carbon on plugs that had on previous flight.
The Strombergh I've has no mixture control, it is NA-S3-B
I'm using 100ll avgas with very good quality control, I’m in flying park and something like 65 airplanes get same fuel and nobody is having problem.
I'm the only operator of the Cub and I fill the plane. My PA14-ET use the same fuel and there is no problem.
In this 8 months trouble the tank has been suppled at least 8 times.
There is 2 different arrangement for carbs:
1. venturi 1-1/4 main #49 bleed air #65 (already test) this combination was flying
2. venturi 1-1/4 main #50 bleed air#65
3. venturi 1-5/16 main #46 bleed air #60 (already test)

what may had happen to the engine reduce the gas eating ?? it has only 225 flying hours