Ford 6.0L Power Stroke Diesel :: 2004 - Misfire / Chugging Usually At A Stop Light?

I've got an '04 6.0 that's recently developed an engine performance issue and I was hoping to get some leads on what to chase down this weekend. The truck has 75,000 miles on it and has been trouble-free since new when it comes to the motor. Recently I've noticed that, usually at a stop light, the idle will occasionally get very rough and the normal diesel "clatter" noise becomes rather rough sounding- almost like every other "clatter" disappears if that makes any sense. Up until last night this was happening very infrequently and usually only for a couple of seconds. I wasn't really sure what the issue was then and would rev the truck in neutral and the issue would go away. This has happened a handful of times in the last month or so.

I drive a company car all week and the truck only gets used in the evenings and on the weekends, and last night my wife and I drove it to dinner. The truck cranked and started normally and was operating smoothly until we got out of our neighborhood (about a mile of driving), then the rough running condition described above surfaced and continued throughout the 7 or 8 mile drive. This was the first time that it ran like this for more than a few seconds. The truck was running bad enough that you could feel the misfire or 'chugging' at speed. When the truck would shift into overdrive and the torque converter went into full lock-up, you could really feel this as the engine was lugging. I tried to keep the truck out of overdrive because it was shaking the truck pretty badly. When we came out of the restaurant I thought maybe the issue would be gone but it did it all the way home as well. Throughout both drives the Check Engine Light did not come on.

When I got home I got my DiabloSport Predator because I remembered it has a code scanner in it. I have never checked for codes before so I do not know if these are fresh codes, but there is a P0282 Cyl 8 Injector Circuit Low and a P1000 OBD Systems Readiness Test Not Complete in there.

While I was in the driveway with the engine idling badly for a few minutes, the issue completely went away and the truck smoothed out for a few minutes. It was like someone flipped a switch and the truck instantly ran properly. After a couple of minutes however, the issue instantly returned. I tried to clear the codes with the Predator but they will not go away. I am not sure how solid of a scan tool the Predator is????

I did a lot of searching on here last night because this is bugging me, and the symptoms I saw on here about the ICP sensor make total sense based on what I am experiencing. People were describing to a 'T' what I am experiencing. However, I do not have an ICP sensor code and when I searched for the P0282 that I do have I read about FICM issues here.

The rundown on the truck- '04 F-250 CC 4x4, truck was bought 10-03 and I THINK I remember the build date as 9/03 (maybe 8/03). Automatic transmission, DiabloSport Predator with 60hp tune, MBRP turbo-back exhaust, everything else stock. Oil was changed about 4,000 miles ago, both fuel filters done about 2,500 miles ago.

A few questions:

Could the ICP be my issue even though there is no code for it? Could the P0282 be coming from an ICP issue?

I've read about early '04 trucks having '03 motors and something about an updated harness for the ICP- could I get more info?

Is my truck part of the affected group with the wire-chafing I read a little about? If so, could that be causing this and what should I look for?

Does the P0282 immediately point to a FICM issue?