[swathdiver]

I’ve noticed a weird voltage change inside the truck, almost like it will run from 14.6 down to single digits, then shoot back up. Once it’s hot it’s steady at 14.8.

Perfectly normal, the BCM controls alternator output. It's called Regulated Voltage Control and Electronic Power Management, RVC and EPM.

 

[swathdiver]

@ryan_

The high trim readings are indicative of a massive vacuum leak or a stuck injector. Fuel pressure is supposed to be 43.5 psi with the engine running.

You can do some level of diagnostics with a phone app like Torque Pro but if you cannot see injector pulse, LTFTs, O2 sensors, etc. you'll need a bi-directional scan tool that can interact with the engine's computer systems.