Have an '04 N/A with 191k. So far I've replaced the PCV valve and MAP sensor as I was getting some bad mileage. Got an EGR code for insufficient flow. Replaced the valve and cleaned the MAF. I had also cleaned out the throttle body around 145k along with swapping out the upstream O2 sensor. I'm now getting an EGR code every now and then. I did not clean out the EGR pipe which goes to the intake. Not sure if this would be the culprit, or if just replacing it would be easier than trying to clean it. I tried some throttle body cleaner on the old EGR valve but nothing really came out. I haven't tried SeaFoam on anything, not sure if that's a better means of cleaning it out.
I've also read that the rubber O-ring around the PCV might be a problem as the PCV-MAP sensor-EGR combo can throw codes sometimes. I did not change out this O-ring.
Let me know if anyone else has had some similar issues or solutions, thanks.
