Did you ever figure out how to fix the problem? I am having about the same issue. A few months ago I replaced my CP3 with an LBZ CP3 because my stock one was worn out. I got updated tunes from my tuner loaded up for it after I installed it. Ever since I replaced it and updated my tunes I've noticed that if I am getting on my truck for more than about 5 seconds it sets off the high rail pressure code (p0088). I can reset it and it wont come back on again unless I get on it again. I am wanting to know what things I can look for to prevent it from happening any more. It doesn't seem to effect the way the truck runs, I just don't like looking at my CEL. Thanks for any help.