I have a 93 Truck with the 3.0. There is a valve that is on the passenger side of the motor near the EGR valve. Toyota calls it a reed valve, but doesn't give much description on what it does. It started making a very annoying noise yesterday. It kinda sounds like you put a baseball card in the spokes of your bike, did 2 lines of blow, and then took off down the street. It only made the sound when the engine was not under load so it wasn't bad when I was moving. We pulled the vacuum line off and plugged it up. I just want to know if any of you guys have had issues with this thing, it's not cheap so I just assume leave it as is unless it is gonna give me problems.