i have been watching for a while saw bthe vid for the vac. gauge it seems to me it is a vac. leak or a lobe on the cam or a valve sticking or burnt to know more you may have to start ripping into the engine to see whats up just take your time and be as methodical as you can good luck

2013 Chrysler 300 touring 1974 Dodge Charger SE. 360-727-8.75-3.23 sure grip 1972 Dodge Dart Swinger 1995 Dodge Ram 1500 4x4