[V8] 1990 v8q trans cold weather behavior

[Ed Kellock]

This has occurred two mornings in a row.  Both mornings were single
digits.

Yesterday with minimal warm-up before engaging reverse, it seemed to
engage normally, then grabbed a little bit abruptly when I applied light
throttle to back up.

Today, the temperature was a bit lower overnight last night, dipping just
a bit below zero, so I let the engine run to warm up until a couple
minutes after the climate control system started operating.  This time,
shift to reverse, seemed to engage normally, then apply light throttle and
it grabbed hard enough to almost make the engine stall.  Backed up a bit,
stopped, shifted to drive, same thing.  Then another attempt at reverse
and this time it did kill the engine.  Restart, shift, apply light
throttle just after shifting into gear and an abrupt engagement again,
with another attempt after that that killed the engine.  I finally backed
up normally and drove around the block and it seemed okay after that.

When I first got the car 5 years ago with about 120k miles I drained and
refilled the transmission a couple times with cheapo fluid in a gallon
bottle, then twice with Mobil 1 synthetic.  Last year I took it in to have
the filter/screen replaced and had the wrong parts and they drained and
refilled with some name brand high mile formula fluid.  Took it back to
them this past August with the correct parts, they changed the screen and
gasket and used the same or similar trans fluid for the refill.   Has been
driving normally until these cold mornings.

I'm going to do a flush/fill with 4 quarts of Mobil1 today to get it back
to where I know the level is correct and give it some more cold-weather
friendly fluid.

Just wondering about that grabbing clutch thing that Dave Head identified
some time ago, or other possible causes/solutions for this grabby behavior
when cold.

Related issue: Ever since they dropped the exhaust to pull the tranny pan
to replace the screen and gasket, the cat light has been blinking.  It is
usually on as soon as you start the car, flashing quickly and all the
while the car is running.  I've assumed it was damaged when they had to
drop the exhaust.  It didn't start doing this until a couple weeks after
the service though.  If it were sensing a true overheat condition, it
wouldn't come on immediately upon starting the car, right?  Today, it
didn't come on until about the time I decided to shift it into gear.  Car
runs normally, good power, no noticeable increase in engine temp, no
smell, good gas mileage (except when I drive it ;-).

Thanks in advance,
Ed