prop and canister setup are OK.
The ignition should be plug and play, and needs no programming whatsoever, even on tuned pipes. If you programmed for the tuned pipe (long), you might loosen one sensor screw and retard or advance ignition a bit. One mm movement is about 3° ignition timing.
I think the carb settings are way off!
Do you use a dedicated line from clunk to carb? NO T-connections there please.
Is the carb filter clean? Check the internal strainer, and use a felt clunk.
Check the carb lever settings and internal parts. Use a carb fuel pressure tester. (may need professional help there)
Some Walbro carbs just do not perform as they should. If nothing seems to work, replace the carb!