I just finished putting my truck back together after diagnosing a similar knock. My knock was pretty light and kind of sporadic at idle but would get stronger and more regular with throttle. I tried a bunch of things to figure out the problem but finally decided that it must be exhaust valve trouble after taking my turbo off. The 'knock' sound turned into more of a 'chuff' sound and the exhaust was coming out in puffs rather than a steady stream. I found a video that someone had posted somewhere of their truck 'chuffing' from exhaust valves sticking and it was just like mine. Sure enough, once I had the heads off and the machine shop looked at them, they found that all of the exhaust valves in one head were sticking open.
I hope it turns out to be fuel problems for your sake but if it isn't, do a little reading about 'chuffing' and see if it rings a bell.