Chrysler Repair: Van chugging / stalling, egr valve, relevant history

Question
My 1996 3.8L T&C chugs and stalls on occasion.  In checking the codes, I found only a 31 along with the 12 and 55.  It chugs at any speed, intermittantly, and dies sporadically, when slowing to a stop - warm or cold.  The only thing consistent is that it's not consistent.  Some work has been done in an attempt to fix the condition, which I will report after your initial thoughts.  Thanks

Answer
Hi Tom,
I enjoy playing '20 questions' but becasue of time limitations and other questioners it is an inefficient way to provide advice. Please let me know all the relevant history. At this point I suspect that the code 31 is not related to the symptoms as much as it is an air pollution issue (fume elimination). My guess is a sticking egr valve.
I await more info, as time permits.
Roland