1995 912UL miss

Could be plug fowling;

What fuel are you using?

Might be better to cruise at 5200 RPM or above.

What is your static RPM (prop pitch)?

Years ago I had an intermittent "miss" in my 912ULS. Always seemed to occur at 5000ft plus, shortly after top of climb/in cruise, over "tiger country". Tried everything (including an AvGas shandy) - still had the miss. Then it disappeared. I now think it might have been psychosomatic ?

When was the last time the carb sockets were replaced?

Just a update on this for those interested. I tried everything I could think of and while checking the gascolator I noticed two thing. The drain was hard to get sealed back up after sumping the fuel, and after removing the bowl it needed a new gasket. I ordered the parts but temporality installed a in line fuel filter.

Since the install of the in line fuel filter it has not missed any. The only thing we could come up with was that possibility that the Drain valve was weak and the mechanical fuel pump was pulling air in to the system. This could explain why the moving the throttle to idle for a bit helped? 

My newest issue is hard starting when hot, looks like I need to run a fuel return line?

Thanks

Mike