/6 runs great, randomly stumbles and dies...???

I suspect the carb too, but I have checked (twice) the carb seal. That's how I found the detached choke pulloff vacuum hose. I just hope I haven't gunked up my new reman carb with s*** because I didn't clean out or change the fuel tank first. I'm kicking myself now for not doing that first, oh well.

I just ordered a brand new fuel tank. I can always use this one for another project probably after cleaning it out, but I want a quick, easy and sure swap when I do this. $ well spent I think.