Truck was running fine before timing belt change, now after it pings in upper gears when under load.
Replaced fuel filter last year, air filter replaced last year. 149,000 miles.
Went ahead and replaced plugs and wires since they were due, seafoamed through a vacuum line, even tried changing firing order according to numerous articles, but nothing helped.
Truck is in correct time, and runs great except for the pinging under load.
Here's what's weird, while testing my coils, truck will start and run on either coil just fine, no pinging. But connect both coils and it pings under load. Plug wires are in stock configuration on coils according to manual.

 

Run the fuel tank down low or almost empty , then get half a tank of higher octane gas. If you currently run 87 go to 89. If the pinging stops or reduces try going to a cooler thermostat , maybe a 180* if it has a 195 in it now.