I dismissed electronic diagnostic tools as unnecessary complexity until a persistent missfire on an International DT466 proved me utterly wrong. | Diesel Mechanics - Chatter Central
Man, I used to roll my eyes at those fancy scanners too. Had a similar stubborn idle on a 7.3 Powerstroke that drove me nuts for weeks. Finally borrowed a buddy's Snap-on scanner and it pinpointed a failing injector control module in minutes. Never doubted the value of proper diagnostics after that.