My uncle told me to always check the simple stuff first, even on a tough job
I was working on a 2015 Silverado with a rough idle, and I spent about three hours checking sensors and fuel pressure. My uncle, a retired mechanic, called and just said, 'Did you pull the plugs yet?' I hadn't, thinking it was more complex. I finally did, and cylinder three's plug was completely fouled. Swapped it, and the truck ran smooth. I guess experience really does teach you to start with the basics. Anyone else have a story where a simple check saved a ton of time?