2001 Dodge Ram 1500 5.9L.. where to start. being 16, gas money is an issue so the tank did run dry a few times. being that, last friday (3-7-14) i replaced the fuel pump. truck ran great!! no problems or check engine light. So one day i go out, start up and drive off. id say about 10 mins into my trip the thing started shaking unbelievably, like instantly. not progressively worse, just instantly shook like crazy. check engine light was flashing, i didnt have my code reader on hand so i googled what a blinking CE light meant. turns out to be a severe misfire. chugged it home, plugged in the reader and got 5 codes. Cylinder 5 misfire, Cylinder 6 Misfire, Cylinder 8 Misfire, Random misfire And Injector 5 circuit open. all in the matter of seconds. no cracks in the distributor, the coil was arcing but i still have awesome spark, MAP sensors voltage was funky... all of the cylinders with the misfires HAVE SPARK. i used nodes on the injectors and theyre all firing right on que, so ive ruled out a short. another thing i found was a snapped ground on the firewall up and to the right of the distributor cap, no clue in hell where it goes or how long its been broken. im truly, and completely mind F***ed. the only thing im coming down to is a bad PCM unit. again, gas money being an issue, i dont have a grand to dump into my "brand new" 01 dodge ram. any help or suggestions are GREATLY, and i mean G-R-E-A-T-L-Y, Appreciated.