no power missfires
had the same thing happen to me. look for trash in the fuel bowl. when trash gets stuck in the float valve it will cause the bowl to overflow and flood . can barely keep it running especially at idle. jack it a couple of time, trash gets flushed out runs great until it happens again. check it out. Or you may be over powering the float valve with your new fuel pump. (max 8 lbs)would act the same way.
good luck.