I have a fuel injected 502 magnum that randomly starts to spudder and cut out then die mostly happens at idle but has also happened one time at wot then I turn the key off and start it back up and is fine for awhile I am also only able to get 4000 max rpms out of it I have changed plugs ,wires, cap , rotor and coil I ran some fuel additive through it for the first tank because it had sent been ran for 2 years but now I have rsn 2 tanks through it and still doing it. Any info is appreciated thanks

Fuel filters may be gummed up from the old gas sitting and now being run, the nasty stuff may have went from the tank to the filter.

Going to want to check fuel pressure as well...but I would be changing the fuel filters first.

I have changed the fuel filter twice already this summer did a compeesion test that was good and cleaned the filter in the bowl that's on top of the motor I was told that's were the fuel gets presherized to go to the injectors

Check your kill switch. Overtime the plastic parts on the lanyard end loosens up enough to cause the engine to cut out or quit. I have had this happen on two boats.

Padraig

Pull, clean and flow test all your injectors.

Lets start by telling us what you have, year, VST or cool fuel, I presume its a 502 MPI mag ?

+1... plus replace you idle air control valve

It's a 502 mag fuel injected w/cross ram induction system I believe the motor is a 92 because that's what year the boat is and I was told he had the factory put it in . Idk if it vst or cool fuel

Check out the fuel rails for a shrader valve where you can check fuel pressure.

Removing and having the injectors cleaned and flowed is a good idea, especially if you dont know the last time its been done.

Check the anti-siphon valve too