Srr, thanks for sharing your progress & troubleshooting results... I dont have an answer but I have somewhat similar issues with my truck... Some of my threads have carburetor info links... I hope to begin rebuilding my Mikuni carb very soon; so far just buying tools & parts to throw at it...

It might be another 2 years or more before small trucks are for sale in USA so keep at it brother... The FSM has a bunch of DMM checks with carb on the truck, worth a look...

Aloha--
George