Truck: 2014 F150 5.0 with 127,000 kms on the odometer. 99.99% of fuel consumed is Esso 87 octane, usually from 1 of 3 stations. Full synthetic oil since new.

Symptoms: I cleaned the throttle body around 100K, did the relearn procedure (twice) had the plugs replaced shortly thereafter, and have been noticing some spark knock/detonation under acceleration since (had not noticed it before)

Aside from switching to a different brand of fuel for a couple of tanks what other steps can I take to track this down?

 

Put a good FI cleaner in the gas such as Chevron Techron and it will help clean up the combustion chambers.