Hi- I recently illuminated the check engine light on my '94 850 n.a, car had no driveability issues, idles smoothly, and gets about 30 mph. Car was warming up in my driveway, light came on. I checked the codes, only 1-5-4 on port 6 came up, for EGR system flow too high. I cleared the code and drove the car for about 1.5 days, then the light came back. I dismantled the airbox and other things in the area of the EGR valve to get a good look, could not see any signs of bad vacuum elbows or lines, can't hear a vacuum leak, and the car idles fine, has no apparent signs of anything wrong. Could the diaphragm in the valve itself have went bad? Thanks for any advice- Brett