engine shuts off while driving- sometimes power seems to sputter

There are a ridiculous amount of possible causes to your concern. You may have an issue with your high pressure oil system. You could have an issue with your low pressure oil system and the bracket that feeds the high pressure oil pump. You could have an issue with the injector control pressure. You could have a FICM (Fuel Injector Control Module) issue. You could have a coolant leak internally in the engine via your EGR cooler or engine oil cooler, causing a multitude of concerns. You could have coking in your EGR system and turbocharger, causing the variable vanes of the turbo to not operate and bind. And on...and on... The best thing to do...the only real thing to do...is to have a 6.0L Power Stroke Diesel experienced technician inspect your vehicle and use their experience and knowledge to get you running right again. I wish you luck!