1-12-2021 This is a New comment, all this will help your performance, but sometimes I have found that the Mass Air Flow Sensor is the culprit with it shuttering or 1/2 second stalls.
2004 Lincoln Navigator. How to fix a stalling vehicle. 2004+ Lincoln Navigator How to.
Two videos - 2004-2006+ Linclon 5.4 liter engine Navigator, Aviator. Replacing or cleaning the AIC or Air Idle Control will do the trick if your truck has 60-150K+ miles on it. This is a typical symptom of many cars that use an AIC.
The second symptom is shuttering or a very quick drop of power while accelerating. The part that looks like it solved the issue is the Throttle position sensor located to the right of the full trottle body (modern carburator). Both of these are perfect for the DYI'er.

The second issue it one of a few items that could cause this issue, but this is the easiest to replace and most mechanics would replace this along with a few other parts like the MAPP sensor and the rpm sensor. Good luck