Dyno run/ missing out maybe? Low hp/tq

First things first. Run a compression test on all 8. Record the numbers and get back to us with them. That will give you and us a good idea of what we're workin with. Make sure you do it with the engine at operating temp. Disable the ignition (remove coil wire). Connect the compression gauge to each cylinder and crank the engine over several times with the throttle wide open, then get your reading off the gauge. Do that for each cylinder. Driver's side bank is 1-3-5-7, passenger side bank is 2-4-6-8. Make sure you record them by the correct number cylinder.