I have a 94 cadillac seville sls it started running rough about a mouth ago I changed to coils and it fixed it but just about a week ago the car started doing it again so I check the coils again the are fine. the enigne is running in default on 4 cyl. The car spit out a P119 witch is a shorted fuel infector so I changed the fuel rail along with injectors and wire harness, put a new fuel filter, I had the fuel pressure tested and it said i was running about 20psi instead of the roughly 42psi so i changed the fuel pump, even changed the computer with no change in the way it acts. I have ran out of ideas can you help me. thanks cadillac tom