86 5kcsq still stumbling when cold

[Kent McLean]

Stacy wrote:
 > Car starts fine, after about 30-45 seconds, the car will stumble
 > and sometimes (usually) backfires slightly when taking off, it
 > smoothes out once the car is moving and above about 2k rpms, once
 > the car reaches about 80% of warmed up (which on this car, is the
 > about 3mm to the left of center of the temp gauge) the problem
 > pretty much goes away.
 >
 > What has been checked so far...
 >
 > Replaced crank case breather, replaced warm up regulator with a
 > known good used one, checked for vaccum leaks at all the normal
 > places on the MC1 (hoses at back of intake, between intake and
 > head, turbo boots etc), new plugs, new airfilter, ...

O2 sensor?  It wouldn't do much until after you start the car,
then it might be cantankerous until it warms up.  ISV - it may
just need a good cleaning. The MFTS (multi-function temp. sensor)
is also problematic - a frequent source of failure that causes
funky problems.  A Google search of the Audifans website will
tell you more.

Have you checked the DTC troubleshooting codes?
http://www.sjmautotechnik.com/trouble_shooting/10vtecu.htm

--
Kent McLean
'94 100 S Avant, "Moody"
'89 200 TQ, "Bad Puppy" up in smoke