I completely rebuilt my motor at 128500k mikes. Since the rebuild its hard to star when cold unless plugged in and my MPG's have fallen back to almost what stock MPG's were. Motor now has 36k miles on it. Why is this? I've completely deleted the EGR & DPF, S&B CAI, 4" turbo back exhaust and H&S XRT PRO RACING TUNER. I'm getting 16mpg @ 70mph empty and 8-9mpg loaded reguardless if I'm towing 2k pounds or 18k pounds. Why is this happening??????