ford f450 will start, if i go into a store out i have to use starting fluid to s

Too many differant things can cause this. Systen should have fault codes, that may help but injectors do fail on these trucks. I reccomend yo find a Diesel Technician. Here is a list of possibilties for hard start issue: Failed All Fuel Injectors Weak Camshaft Position Sensor Signal Low CKP Sensor Output Low Compression Plugged Exhaust System Failed Fuel Injection Control Module (FICM) Open Fuel Injection Control Module (FICM) Wiring Low Fuel Pressure Poor Fuel Quality Leaking High Pressure Oil System