P0278 code

[Capt Trashy]

Ok, I've read a lot of good info on here but never seen anyone give the solution to this code. I bought a used 05 F350 and everything has been a nightmare so far. The turbo was plugged, valve cover leaked, ipr was leaking through the harness. That all was fixed by the dealer who sold it to me. Well now the EGR cooler went out 5k into driving it low and behold why...the EOT delta was 40 degrees at 70 mph on the highway. I found this by reading about it and buying a Scangauge.

Knowing this and not having adaquate tooling I took it to a pretty diesel shop here in town. I had already ordered the BPD solution kit for The EGR and Oil Cooler. Well it all went in and during the test run it threw a code for cyl number 3 and 6. Well 3 cleared up, figure air in the system. But 6 won't go away, due to getting p0300 and a p0306 code(which hasnt come around in about 1500 miles after Rev-X, and lucas oil fuel conditioner) I ordered a ford injector, it went in and the code went away for about 15 min of driving. I leave to go drop my borrowed car back and get a call from the mechanic saying it the code came back, and he suspects the harness, so I said ok get it.

Well that didnt fix it, I can't see it smoking, but the idle changes about 30 seconds into running it. It definitely runs rougher, the balance test shows 6 continuously 100 RPM higher than the others. They are suspecting a base motor issue, but the truck hadn't had the code before going in. Last I heard they swapped FICM's with another PSD while it was there, still the same.

Any help is much appreciated!