My son has a '95 7.3L PSD and we've had few problems with it overall. He called from college the other day to tell me that the truck was running really rough and was missing and he couldn't get any speed. He pulled into a K-mart, killed the truck, started it back and it ran fine for a few minutes then started doing it again. I trailered the truck home and ran it a few times around here. Mostly it ran fine, but several times it did run really rough and I could detect a dead miss and rough idle. I assumed it may be the FICM, but decided to pull codes instead. My Snap-On scanner with the KOEO mode pulled only one code: P1111 System Pass. I pulled the memory codes and pulled a P1282 excessive ICP and a 1211 ICP pressure above/below normal. The FICM had been replaced years ago and I replaced the IPR as well, so I assume these codes may go back to there. Regardless, I cleared the codes and did both an KOEO and a KEOR test and pulled no code except the P1111 System Pass.
What is a P1111 anyway? Could it be that my problem may be something simple like bad diesel or dirty filters?