Fuel issue, does not turn over

I've replaced all the spark plugs, their wires, distributor cap and rotor, exhaust manifold gasket, a fuel line, fuel filter, vacuum lines, fuel injector, a throttle body repair, and texted many sensors. But, it still doesn't seem to want to turn over. I tried replacing the pump, but I couldn't get to it since the lock ring was stuck due to rust and it really didn't seem bad and was giving out pressure since it would still start from time to time, but not consistent or without a great deal of work. Any suggestions?