Flywheel problems

1995 tacoma 4x4 Automatic w/ 149,000 miles
It keeps breaking flywheels? I've replaced two flywheels in the last 3 years. About to replace another. After 2nd flywheel, preformed a major tune-up(plugs, wires, belt, timing belt, and water pump). Was told a short in wires caused the truck to backfire internally, which caused the flywheel to crack? Know I'm not to sure of that.
Please try to help. Was also told it may be a thrust washer on the crankshaft causing it to move back and forth a little? :D