Though you're motor may be beat up, didn't it run well before you changed to the new carb and intake? My guess is you need to TUNE the new carb, and you will probably have to tune the carb on the new motor too. If you want to experiment while you're waiting for your new stuff, either put your original carb back on the old motor and see if she runs better, and/or, move the float and jet (and air filter if it is different) over from the old carb to the new carb. My guess is the float setting is different on the new carb, move the float, move the setting. Or the jet could be not exactly the same size. My guess is it has more to do with the carb swap than the new intake or how beat your motor is. Good luck with your project...