Soo finally got my 6.0 back together. new o-ringed heads, studs, oil cooler, egr cooler delete, new inner fenders, new heat box <-- (dont ask--lol) rough time. Anyways, took a bit to get the oil pressure up to fire. It fired up, idled smooth for about 2 mintues, then all the sudden started surging and loping. Shut it of, started right back up, idle smooth for about 5mins. took it for a drive. Had no issues driving. icp, ipr, vgt, ficm, ect.. all looked good driving. Got back, let it idle a bit. no issues. shut if off. I let it sit overnight. Next morning, went to start it, took about 6sec. Fired up, started surging / loping again. Noticed the Icp duty cycle was fluctuating between .14 and .30. When temp it about 130 degrees. loping and surging went away. Icp stayed at .30 ipr was about 1200psi. Got up to operating temp. Icp and ipr wouldn't go below .30 duty cycle and 870psi. Got back shut it off. Wigged the Icp plug. and started it up again. ICP still at .30dty but now the ipr reads 634-650psi at idle. Could this be a faulty icp / pigtail issue? Edit.. There's no issues when driving it.. icp is about .42 at 65mph 1100-1200psi. let off accelerator. icp drops to .30 sometimes mid/higher 20's 870psi. when it acts up. first time drive. icp was at .40-42 65mph 1058psi. let off went to .24 and ipr 700ish psi.