Have you looked at Herko? @Doubeleive seems to like their offerings:
codes p219B and p2635
More things to get in the way before my cross country move... lol Lets go back 6 months... I was getting a check eng and P219B code sometime back then. I would reset them and it would be fine for a month or so. At that timen I changed plugs and wires I noticed the passenger side had normal...www.tahoeyukonforum.com
I haven't... 120$? that is a good price.