What do you mean by "if I let go of the gas the engine can catch itself"?? What happens if you just leave the throttle at full, does the engine startmissing and thendie shut offcompletely, or does it just start bogging but keeps running? If it dies, (whats called a "flame out").. Your probablyrunning it out of fuel and your High Speed Needle (HSN) istoo lean.. Now, if it just starts bogging down, you could have the HSN too rich, and it's overwhelming the engine with fuel (or trying to flood it).. And for my third guess
You could just have the transmission set to go into 2nd too late, but it sounds like the engine isnt tuned for full performance.. Remember, if ya need to richen the HSN, turn the screw counter clockwise.. If you need to lean it out, turn it clockwise.. Only adjust in 1/12 increments.. Think of the needle housing as a clock, and just adjust the screw an hour at a time in the direction ya need, then run the vehicle for a minute or two so the change can take effect, then make another adjustment, etc.. It sounds pretty close, so it may only need a small tweak to dial it in! Also, be careful not to run it too lean, cause it'll get hot and could damage the engine.. Either use a heat temp gun, or some spit or water and put a few drops on the top of the engine cooling "head".. If it sizzles, the engine is too hot.. It should evaporate in about 5-7 seconds.. If it takes longer than that, to evaporate,the engine probably isnt running at top performance. Good luck and let us know how it does!!