all cylinders misfiring only a p0300 code !!help me!!

Changed plugs,cap,coil,wires,rotor button,air filter,fuel filter,tps sensor,check fuel pressure50-55and holds,and I have no clue what to do next. Does anyone have any advice? It would be much appreciated

Pull and clean your MAF...(brake clean and a tooth brush) If that doesn't work, it most likely is your injector unit...

double check that the plug wires are in the right spots on the distribitor