the motor is missing and will not idle. its like the plugs are not firing. on 1999 Ford F-350 Super Duty

It is 1999 gas v10 ford 6.8 liter, 24,000 miles.

2 answers
Have this checked out before parts replacement. Mechanic with a good scanner can save you some money! There are a few possibilities for rough idle. Only 24,000 miles,, most likely a vacuum leak. Obviously sets around a lot, check for any signs of mice under hood, they love to hide out in engine compartment and chew on vacuum hoses etc...
Ignition coils are the most common issue, all the time.