Originally Posted by Andy1023
Thanks for the insight. Oil level is fine. I guess it could be pump related.
If your oil pump isn't maintaining adequate pressure, you should be able to tell from the oil pressure gauge. If you're reading high pressure you are likely OK in that area.
It could be many things, but I personally doubt it's a valve problem. Those tend to be more continuous rather than intermittent.
It could be something as simple as detonation (pinging or spark knock) that is more common under load, and goes away when you take your foot off throttle. It's more common when engine is running hotter so check to make sure temperature gauge is normal.
And as others have mentioned, it could also be an exhaust leak. They are much louder under load and less so when you ease up on accelerator pedal.
Since Ford couldn't find anything wrong, I would try one tank of higher octane gasoline as a test. If it is related to detonation, the higher octane should help reduce noise under load.
By the way, I assume your engine is stock. Any mods (tune) could introduce too many additional variables.