My VX failed smog recently due to clogs in the intake manifold EGR ports so I just thought I'd share how I fixed this problem. There are various methods of cleaning the carbon buildup but I chose to drill the existing welded plugs, clean them out, tap, and plug the holes up. It was best to remove the entire intake manifold and make life a lot easier. Seafoam and carb cleaner sat inside the manifold overnight to help break up the gunk. Using a 5/16 inch drill bit, all 5 upward facing plugs ere drilled into the eyeballed center of the main EGR channel. I used various wire brushes and cleaned the passages through holes that were drilled. 4 cans of carb cleaner, intensive scrubbing, compressed air, and water pressure later, the manifold was completely clean removing what looked to be a pound of carbon gunk. I tapped the holes with a 3/8-16 tap. Each hole was then plugged with a 3/8-16 hex key heads and high temp sealant on the threads.