Looking at the intake and all that, I am thinking that the crud comes from both the oil fumes and the EGR. I vented my Crankcase Vent on my Powerstroke to the exhaust and found that the exhaust now has that same crud. Maybe we could reroute the crankcase to the exhaust and have less buildup in the intake tracks?

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01 Ford Excursion Powerstroke
99 E300 Turbodiesel
91 Vette with 383 motor
05 Polaris Sportsman 800 EFI
06 Polaris Sportsman 500 EFI
03 SeaDoo GTX SC Red
03 SeaDoo GTX SC Yellow
04 Tailgator 21 ft Toy Hauler
11 Harley Davidson 883 SuperLow