Personally as long as the truck is in sound mechanical shape and routine maintenance has been performed then a tuner won't be an issue.
To do a compression test at home you need to go out and buy a tester gauge.
Remove spark(s) plug and put adapter in the hole and crank the motor.
Another GOOD investment is a Haines or Chilton repair/service book what can be purchased/ordered at an auto parts store or online.
Peace!
