Are you sure it's the CTIS manifold blowing the air and not the dryer or the relief valve? I thought the same thing, but it turned out to be a faulty air dryer blowing the air, along with the emergency relief valve. I found a complete replacement NOS dryer unit on Ebay for a very good price, which solved most of that problem. i also ended up replacing the unloader on the compressor. The unloader was leaving the compressor running when the tanks were full and then the emergency relief valve was operating. I also had a similar problem with the steering dumping air, but mine was mostly when i turned close to full either direction, but sometime it did it without turning. I jacked up the front of the truck so the front wheels were off the ground. I then removed the air inlet from the steering actuator and put in several large squirts of air tool oil. I then re-attached the air supply, fired up the truck, and turned the steering wheel full left and then full right for about 50 times, until the problem went away. i havent had any issues with the steering since.