lost of exceleration jumping tack

What is your question?

driving on the hiway 60 65 the car will drop speed like theres thers no gas coming through the carb but if you pump the gas it comes back does not happen all the time i have noticed it happens when tank is low my other problem is the tack it jumps then it goes to the right rpm then jumps again could it be a short or ? and how can i fix either problems or check for