Earlier this year after having the LIM gaskets replaced, all was good for a week or two. Then I get a SES light and have it checked, it's for the EGR. I forget the exact code but it may have been a P0404. So I let it go for a while, then a week ago I replaced the EGR valve entirely as cleaning it didn't help it any. I got the valve from 1a-auto and a genuine gasket for it from the dealership. I cleared the codes myself and about halfway on my way to work the SES light is back. I get home and check it and it's a P0401 (Insufficient EGR flow). I've checked all vacuum lines, the electrical connections on the valve look good. I also ran the car without the EGR valve on at all and it nearly stalled, so I plugged the intake side of it and the exhaust side is also functioning with very good flow it seems. I should add that this is a 1998 GTP. I have checked and replaced the PCV valve, but the original O-ring is still on it. I have also checked the vacuum line going to the MAP sensor and it seems to be fine. Also, after clearing the codes, I believe I have lost a couple of MPG's as well. I'm at a loss of what to do and I really don't want to take it to the dealership, again...
Thanks for any advice
