93 explorer hard start then ping

[PJRaces11]

ok lets see i got a 93 explorer 4x4 4.0 automatic and when i just replaced the fuel pump the fuel filter,cleaned the MAF, head gaskets, rebuilt all the injectors, cleaned all the carbon off the valves and pistons, replaced the lower intake gasket, replaced the upper intake gasket and all new plugs and wires all from the ford dealership but now when i get in to start it the truck just cranks and cranks and cranks it stumbles to start then dies then u crank more and it does the same thing then finally it starts the truck just started doing this after we had all this stuff replaced on it also when it is running the truck will ping if you step on the gas it used to be bad but it got better when all that stuff was replaced im stumped onto why it is hard to start and pings like this i was wonderinf if you guys had any suggestions someone said the pump could be a faulty pump but im not sure can you let me know why its doing this or where to start thanks alot