The hissing sound sounds like its coming from under the driver side of the throttle body, and the vacuum line that looks to connect both secondary intake solenoids doesn't have any suction/pressure. I am able to clean the EGR valve correct? I've noticed it smoking more and more gradually. Could a vacuum leak cause that? I noticed that the o2 sensor can be tripped cuz of the solenoid. And said to check my lines before the o2 sensor. But I also read that the EGR can cause smoke. What a learning experience (lol).