I have a 2002 F350 with around 102k miles. It has a rough idle @ start-up after sitting overnight. It will clear itself up after driving for about 2 miles OR plugging the block heater in overnight. I thought with the plugging it in solving the problem, glow plugs may be the problem. I had it looked at today and was told the glow plugs are all good and the problem is likely the injector (s) but have to run a test to see which injectors are bad. Would the injector problem go away with plugging the block heater in ?