In regards to the R word, used in context as a known definition of a part can happen, There are other terms one can use but the common definitions of some things use the potentialy offensive phrase, Cheers to ToyotaMatt for offering a more sensitive way to describe when the time arises, I would...
I agree the symptoms of running good, not running good, indicate fuel delivery and given the time sitting I would bet the mechanic had carb working, you stated such, ran good, then it picked up crap in a fuel line, pump, tank and did not run well, entire system needs to be gone thru, carb...