ford diesel truck 7.3 engine that won' t run?

[jan_dxtr]

I have a 2002 Ford f350 crew cab dually diesel 7.3 that won't run, have had it at the shoe for three weeks and they still can't find the problem, they are super good guys but they just can't seem to locate the trouble, they also charge 100 per hour, think they will charge me this while looking for the problem, no question is should I take it to another shop, they are nice guys but am still walking and getting old, don't want to make they upset but business is business, any ideas