My engine started making a wierd noise , was afraid it was one of the roller rockers , its kind of a warbling noise , like a piece of plastic being struck with another piece of hollow plastic. I touched the valve cover but its not vibrating in any way to corelate with that noise . I did find however that the egr/air (not sure what it is) on the driver side header seems to be making the noise and is vibrating. It has what looks like one of those black one way valve things on it (like the one on the air tube of my 84) attatched to a piece of high temp hose. Anyone have any idea what might be making it make this noise ?? Thanks in advance you guys , you are all a great help.