Dodge Repair: TROUBLE CODES P0300 P0304 P0308

Question
Hi I have a 2002 Dodge Durango 4.7L and have been getting trouble codes of P0300, P0304, P0308 I just change all 8 coils and all eight plugs. I erased the codes and let it warm up then it came right back on. I can't tell if the cylinders 4 & 8 are not getting spark or not getting gas. How can I find out what's happening

Answer
Hi Adrian,
I would believe that if there were no/poor spark on those cylinders that you would get an 0354 and 0358 code which points to the primary circuits of the coils. It might be fuel injector so if you removed those plugs you could check to see if the they looked "wet" which might implicate the injectors leaking excessively. While you have the plugs out you could check the compression of the cylinders with a pressure gauge to see if they were at least 100 psi.
Those would be the next things to try.
Roland