Diesel Bombers - Does this seem like just injectors or FICM

Just changed injector 7 about 2 weeks ago and had some misfire still going on. went to the mechanic and had it scanned and he brought up a screen to show each injector showing "0" (which is normal viewing on the screen) and when the misfire went it showed injector 1 and 8 going into the negatives. So my obvious guess is they need replaced. But what also caught my eye is every injector was dropping like that but only 1 and 8 were making a misfire to where you could hear it. it showed injector 7 did it once also. all of them were random and fluctuated. but 1 and 8 were the worst. So any guesses if its just each injector starting to finally go? or could it be the FICM just messing with all of them. I had two codes. One was for MAF sensor. i already know its just dirty. alot of dust and sand particles in the air down here where i am based. And the other one is P0284. Which is injector 8. But surprised i didn't see a code for injector 1 considering it was worse then 8 is. Truck just rolled 127,000. So just seems kind of odd to me. Fuel filters done about 3-4 weeks ago. Oil changed about 2 weeks ago. And added Rev-X for the first time 1 week and 1 day ago. Since fuel filters have been done about 4 weeks ago roughly i have only put about 2,000 miles on it. Use motorcraft filters. Dealer did the oil change since they owed me one so i don't know what oil they used.