94 5.2L Magnum running rough

I would surely replace the plugs anyway. Good old Autolite 3924s work fine in these engines so there is no need to use expensive ones. It is possible one of the plugs has cracked porcelain/insulator from removal & installation. A spark plug socket should be used on these, it prevents this from happening. If you don't have one, get one. I believe it is a 5/8'' socket. Bad plug or plugs is more than likely what is wrong. Fuel pressure should be right around 45PSI at the fuel rail on a Magnum engine.