My 04 ram 5.7l died at stop sign now won't start

Usually, when things like this happen and no associated loud bangs or shimmies associated just before then you can more than likely rule out mechanical problems. What led you pull off the valve cover? All valves under compression will likely be compressed at different values. I would start back at something simple like spraying starter fluid down the throttle body, crank the vehicle n see if she starts or at least breathes life. Is the check engine lite on? Hows the power band been when accelerating? Did she idle okay? Go for the simple stuff first