The 5.4 is well known to have a combination of problems.

Since the oil path goes from one head to the other, any loss in pressure can result in lifter noise.

But lifters aren’t the only possible culprit. As it could be chain tension. Phasers. The oil pressure dummy switch won’t illuminate the warning light until the oil pressure drops below 12 psi. So your gauge will remain halfway till then.

Yet the engine can tick around 16-20 psi.

The test is to see if the oil pressure maintains above 16 psi.

First check hot oil pressure At idle.