Sorry to disappoint, car still stalls and P1406 returns. So far I have cleaned EGR, changed PVC, cleaned MAF, but problem persists with random stalling and check engine light comes up. Question: Can I drive the vehicle with EGR disconnected? Some mechanics say EGR can cause the stalls, is that true?

I'm thinking if I disconnect the EGR and car doesn't stall, then it'* a bad EGR and I'll spend the $150 to change it. If car does stall with EGR disconnected, then it'* something else.

So it stalls with the EGR connected? But not disconnected? I'd be more tempted to replace the EGR now, even if it might not be the culprit for the stalling. It'* being reported as bad, and isn't an uncommon failure when that code is present.

Fix that, then let'* move on with the other issues.

Sorry for bringing up an old post, but I like to share on the solution: it is a bad EGR valve that'* causing the stalling. I drove Dad'* 88 for one week and notice the car stalls mostly during coasting (i.e. not applying any gas) and when slowing down almost to a stop (brake applied). Disconnect the EGR connector and drove for one week and car never stalls, even though the check engine light is ON all the time (as expected).

Because new EGR is $150 too expensive for this old car, I finally hit the salvage yard and found a replacement from a 80,000 miles 1995 Buick LeSabre for $20. Installed the EGR, disconnect the negative battery cable (to reset PCM), and car has been driven without problem for a week now. So I assume faulty EGR is the root cause of this random stalling. Thanks for all the help and accurate information!!!

Thanks to you for reporting back what the problem was. That helps all of us!