Wild Bill, you are absolutely wrong about "those two screws". You need to learn more about them before you make such comments and lead someone to think they will make a difference. They will have NO change in the running of the engine at speed. They are idle mixture screws. They effect the idle circuit and transition circuit only. They have ZERO effect on the main circuit.
Funny, after adjusting those 2 screws mine runs excellent now, when those were out of adjustment I had power loss, hesitation problems, etc. Sounds like you need to learn about carburetors before you go trying to yell at someone and tell them what they don't know. Obviously you don't know me, and you don't know about carburetors, or you would know that getting those mixture screws set right or wrong will either cause problems or will fix the problem.
You said it....Mixture Screws. Air/fuel mixture.
I had the exact same problem with my 84 B2, same engine, except I have the manual transmission. Until I got those 2 screws adjusted and bypassed the stupid choke crap I couldn't hardly get any power out of the engine. After several adjustments to those screws it runs great and have all sorts of power and I'm running slightly larger tires as well.