Friend of mine has a '97 perpetually in limp mode because of EGR codes.

I originally got two codes - P0400 egr system malfunction and P0403 egr low flow. I removed and cleaned the EGR, reinstalled it, and eliminated the low flow code but can't keep the 0400 code cleared.

If I start the car and let it idle after about 30 seconds I can see the intake flap close. It stays fully closed for about 2 seconds, then snaps back to full open and the cel / code come on.
If I clear the code, start the engine and immediately start driving it will not throw a code and the car runs great until/unless I let off the accelerator and it drops back to idle for 30 seconds or so.

The CEL was on when he bought the car a year ago and seller told him it was just a glitch in the computer that didn't effect performance. So, he's always thought the car was supposed to be this slow...

Is there any way to do an electrical patch (as I've done on my '98/'99) /or/ have the computer tuned to ignore the EGR altogether?

Just trying to help a friend out. Really annoying to know the performance is in there but not be able to get it out!

Thanks all.

FMB