Hello to all, I'm new here and any input would be helpfull and appreciated. I have a 99 E450 box truck I am having problems with. I bought it a no start, it had died going down the interstate and they put a new high pressure oil pump on it thinking that was it. One of the high pressure oil lines blew off and it wouldnt start and thats how I found it. I bought a new fitting for the pump that the high pressure line locks into because the one in it was missing the retainer ring that keeps the line from blowing off. It runs again but misses bad when cold. I pulled valve covers and unplugging injectors one at a time found that 4 cylinders were missing. The poppet valves on the injectors were worn and i shimmed the armature plates .0015 on 4 injectors. It runs fine hits on all 8 but hasnt a lot of power although I have never driven a diesel that felt to me like it had any power. You pretty much have to keep it floored to do 70 and thats with no load in the box or being pulled behind the truck. Besides that somewhere along the way i pulled 6 injectors out, took them apart, blowed the nozzles out and put them back together. I put them back in the engine without putting new orings on them. I did that to them because I was thinking blowing the nozzles out was helpful. Now I dont necessarily think that. I only did 6 because the front 2 are real hard to get to. Now I have a service engine light on that I didnt have before. I took to dealership and they said code P 1211 and he also said that it had a code for #5 injector when the key was on engine off, before warming the engine up or anything. The light doesnt come on until after the engine has warmed up and he said the light was coming on becaue of the P 1211. He said he thought I needed to put a new ICP Sensor in it. He said it was reading 4 hundred and something at idle and 22, 24 26 hundred while reving it up. I'm thinking since the light didnt start coming on until I worked on the injectors that maybe I need to put new injector O-rings on it first but I'd like to hear what others think about it. Thanks ahead of time, if you know something please tell me I'd like to hear others thoughts on this as I know my thoughts are often not good enough.