I have a 1996 F-250 and 2 weeks ago my truck ran like crap

with only 150,000 miles on it. After trying to figure it out by myself for a week with no success I gave up and took it to a shop. They had it for 2 days before they called me and told me that the main wiring harness was burnt and the wiring harnesses for the glow plugs needed to be replaced. When I dropped it off there was a customer that had the same problem at 100,000. Has this been a problem with anybody else and if so will it be a problem in the future? It's costing me $2,000 to fix it. Damn