The Glow Devil should do the job, and are only available direct from Sonic-Tronics. I use the Glow Devil R/C long and do a lot of others. The Thunderbolt plug is available from Mikegoesflying.com, I think it's called. You may find out for sure by searching this forum. get on the Sonic-Tronic website and sign up for an account as they sometimes email out discount codes that are almost like buying wholesale. Make sure of the spray bar hole at this point and put another quart through it if necessary. Flight loads from airplane weight, drag, and a bigger prop with more pitch will affect it. If still on a test stand it should start easy, lean out a bit if fuel line is light pinched and go back to the setting immediately, and should lean out and quit quickly and cleanly when the tank empties. If the engine stops with the piston at the top of the stroke consistently, run it some more. I have been working with a OS.35S to put in a Nobler ARF and thought it was a low time used engine, but in reality I think it had never really been run and had similar difficulties as you have experienced, and it just took about 6 or 8 tanks of fuel to get over the hump. Starts easy and quits cleanly now so beck in the model it goes!
Type at you later,
Dan McEntee