Wont start I think it has bad fuel injectors, it will want to start just wont combust

Check; Injector pulses good ... Fuel in the combustion chamber ...
petrol smell from exhaust.
That should tell you if there are crank pulsesfor the injectors

fuel pump gets fuel to injectors and into the combustion chamber

without fuel in the combustion chamber the motor wont run

that would effect any cars performance for sure

code p 0307 is misfiring on no 7 cylinder ====causes --- engine mechanical fault ---wiring---ignition/ fuel system--injector --ECT/MAF sensor---ECM
look for low fuel pressure or ignition control module

The prevalent cause is the fouling of the O2 sensors in the exhaust pipe and the catalytic convertor(s). This usually caused by the fuel not burning correctly in the combustion chamber. And this can be caused by: bad/no spark in combustion chamber due to weak plugs or electrical going plug coil packs; partially plugged fuel injectors and result being too much un aspirated fuel entering the combustion chamber; bad or old fuel, improper fuel octane for engine.

Suggest you fuel up asap with PREMIUM fuel (for 1 tank) and 1 can super concentrated injector cleaner for next 2 tanks. Check air filter clean. Check air intact air analyser sensor wire is clean, pull the plugs and check condition and gap, replace them if fouled or worn.

Yes, it IS normal for a powerstroke diesel to require more revolutions of the motor to fire than for any gasoline engine. Combustion in gasoline engines is stimulated by spark plugs and many gasoline engines will start with little turning of the motor past the position where the ignition timing creates the spark and combustion occurs. Combustion forces the engine to continue rotating and combustion in that and other cylinders becomes a perpetual event. A Powerstroke Diesel engine requires more revolutions and speed of revolutions to create the heat necessary to cause the diesel/air mixture to combust. ALSO, the diesel is injected into the combustion chamber, at high pressure, by the injectors. The injectors are electronically controlled and the Fuel Control Module (computer) (also known as the Injector Control Module or ICM) tells each injector exactly when to open and inject diesel into the combustion chamber, as well as for how many milliseconds it stays open (how much fuel will be delivered). Summary, a powerstroke diesel will only begin the perpetual combustion process when the motor is turning fast enough and the pistons are compressing the volume of the cylinder into the tight space of the combustion chamber rapidly enough to create enough heat for the fuel to ignite and begin creating power to turn the motor without the aid of the starter. IN ADDITION, a Powerstroke will NOT start at all with weak batteries. Not only does the motor need to revolve rapidly in order to start, the injectors require a MINIMUM voltage of MORE THAN 12 volts in order to activate (open). The exact amount of voltage required can be different, depending on the Fuel Control Module (FCM) or "Injector Control Module" (ICM) type that is installed. (Note; terminology for the FCM / ICM tend to depend on who you are talking to, what resource you are reading, etc. They are the same thing.) If batteries are weak, the starter uses enough amps to drag the voltage down and, even though the starter turns the motor fast enough that any gasoline motor would fire right up, the ICM will never send the signal to the injectors for them to activate so, the cylinders never get any fuel and the motor never fires. I hope that helps. Yes, a 7.3L diesel will normally need to turn with the starter for longer than your gasoline fueled V10.

Engine does not crank (Does not start)
1. Starter and starter relay
2. Neutral start switch circuit
No initial combustion (Does not start)
1. ECM power source circuit
2. Ignition coil (w/ Igniter) circuit
3. Fuel pump control circuit
4. Fuel Injectors.
No complete combustion (Does not start)
1. Fuel pump control circuit
2. Ignition coil (w/ Igniter) circuit
3. Fuel Injectors.

Tried the injectors or sparkplugs? It can only be fuel, air or spark that's not present for the combustion triangle.

Sparkplugs first, then injectors.

Have you had them check the fuel injectors? Might need new plugs as well. The dark smoke it the casued by flooding it when youre trying to start it and it has to combust all that fuel. The fuel pump might be going bad as well. Have them done a fuel pressure test? I'd need more info on what has been done to narrow it down a little more.

check for injector pulse, if the injectors are not powered then no fuel will get to the combustion chamber.

verify that injectors are getting signal to squirt fuel into the combustion chamber