Engine Skipping

[teched]

My buddy has a 1992 Ranger, Manual Transmition, 2wd. It has had an EGR code for quite some time, but it has not effected it from running. About a week ago it started skipping and stalling. We checked the coil packs and found the one that fires the passenger side to have only spark on cylinder 2 and 3. Cylinder 1 and 4 are dead. We changed the coil pack with a junk yard part with no change. We changed the module that is mounted to the intake manifold with a junk yard part. We greases it up well with dielectric grease still no change. We changed the ECM with a junkyard part with no change. We disconnected the plug to the passenger side coil pack and checked the connector for power. All three connections have power when the key is turned on. We are down to a possible fualty wire or bad ground. This is like looking for a needle in a haystack. I read alot of the other simular posts but I am still not sure if they apply to this situation. PLEASE HELP. Thanks