I only get a CEL when I am on the freeway doing around 70mph. Once I decelerate the CEL goes off. Not sure why that happens. Maybe the header is scavenging more exhaust and allowing the engine to breath better? We used to pull the O2 sensor out of the exhaust stream a little bit with a spacer on turbo cars. Not sure if that would work in this truck. And yes its an 85'.
