I have a ST 3000 that is giving me fits. I have done a search on this site reading all I can. Here is a brief of my engine. Starts first flip every time, runs well trasitions well, BUT it all of a sudden quite with no warning. at different times in the flight. No spuutering or rough running, just like it ran out of fuel or blew a plug but both are ok. I have read that i I switch to an OS 7D carb it should clean up my problem. On hand I have a 7L carb from an )S .61 sf. what is the different in carbs. Both the ST and OS 7L look to be the same size and fit interchangably. I am going to try it in the AM but what is you 2 cents worth.
Dave