Slow acceleration hesitates and misses when accelerated, code PO300

My daughter in law came home from work and said her car wont run.I drove it and slow acceleration hesitates and misses when accelerated. Threw a po300 misfire code. Prior to that it showed throttle position sensor so I bought new plugs and throttle body. I have checked the catalytic converters they're good. No leaks anywhere. All plug ins and connectors are good. Checked injectors there clean all wiring seems to be good. MAF sensor is clean and good connection. I even checked bolts on intake to assure it's tight and cant leak. When you start it it will sit and idle perfect then push the throttle down about quarter to half way and it sounds like a 4 barrel with that bogging sound. I'm thinking it's a fuel issue some how injectors/injector and or filter or fuel pump. Please help. Thanks in advance.