91 dodge ram b250 wont run

ok so i replaced starter, battery, rotor button, distributor cap, plugs and plug wires, coil and fuel pump. the van tries to start it is sparking getting gass and all but the starter sounds a bit slow what could this be?

any ideas why it wont fully start up

Is the new battery charged?
Are all of the grounds connections clean and tight?
Is it a new or rebuilt starter?

yes battery is charged, all the connections are clean and the starter is bramd new