I have an 07' Colorado Z71 I5 with unknown miles. Engine runs great for now but I am getting a good bit of oil coming from the valve cover vent hose to the air intake box. I checked the intake vacuum hose for suction and it is good. What are some things that can cause the pressure to build up enough to puke oil from the vent hose on the valve cover? Thanks for any help. I went ahead and chemtooled the heck out of the TB and it helps. Going to see exactly what code it throws "if any" later today.