[s-cars] Blink 4444 yet Motor Still Stumbles - Code 2413 Gone

[Mark Pollan]

I posted earlier that I was throwing code 2413 (MAF) and still am - but
getting close to was - hoping it is as "simple" as the MAF.  I will be
trying a known good MAF soon as I can hook up with a local lister (Thanks
Mark T.)  I cleared the codes and went for a drive (albeit a short one - 10
minutes or so).  Car stumbled while coasting to a stoplight and recovered
(RPMs dropped to about 300 then surged to 1000  and settled in at 800).
Pulled codes when I got home expecting to see 2413 but 4444 came up.  The
stumbling fairly well goes away with a warm engine.  Would a bad 02 sensor
be a possible/probable cause?  Did I possibly not drive long/hard enough to
register codes?

I'm at a loss.  What gives?  Any and all thoughts appreciated!!  I did clean
my ISV several times.  BTW, I am running MTM 1+ software.

Best regards,

Mark Pollan