2004 club cart very hard starting. Spits and sputters and back fires

Have replaced carb, fuel pump, spark plug (has nice blue spark) new filter fuel lines. Have to manually turn throttle all the way off and very slowly open it tell it fires. Then gradually open Intel it catches up with the throttle position. If I accelerate to fast it spits and sputters and back fires through the carb. Runs good at any consistent RPM but won't accelerate. Also dump old gas and put in fresh. Any one have any suggestions? Thanks in advance.