getting truck back from dealer tomorrow. it is a 2008 lmm. it was in for a p0401 and a p0087 code. (egr and low fuel rail pressure) it would only come on when you are pulling a load. you can rape the truck when it isn't loaded and it won't come on. the dealer said they ran multiple test and it passed everything. could this be an injector issue or a pump issue. what i have done is the ppe fuel pressure relief valve, air raid cold air, magna flow 5-6" exhaust, and a tsperformance mp8 box. the code will come on with the box off also. (i took the box off when took the truck in.) (changed multiple fuel filters for the p0087 code also). what do you guys know about the ppe hot race box and the dpf delete pipe? would deleting the dpf pipe help at all? thanks for the help.