My '89 did much the same thing and the shop diagnosis was
the air mass meter.

With a new one, the car runs quieter and maybe a little better
power-wise.

Allan Ballard

some additional information....

Checked all wires and hoses, everything seems secure and intact. Measured
the AMM heater pins, correct resistance. SAme with the O2 sensor heater.
From past experience, I know that if the AMM is disconnected, the car is
almost impossible to start, yet this morning it started easily when cold,
and ran fine last nite on the way home. Granted, that's not a guarantee that
the AMM and O2 sensor are good, but it seems to clear them of blame for now.

The manual mentioned "low fuel pressure" as a cause. Both pumps and the
filters were replaced about 1.5 years ago, and if that were the problem now,
I'd expect to have lost power on acceleration last nite, which didn't
happen, even when going uphill. Similarly, if there was a fuel delivery
problem, like a failed injector, I would have noticed the loss of power.
Same with ignition (Plugs and wires changed a few thousand miles ago)

I cleared the 2-3-1 code this morning before the cold start, and the "check
engine" light never went off after starting the engine. Seems that if it was
actually sensing a rich or lean situation (say, from a stuck injector), it
would have taken a few minutes for the system to realize it, so the light
should have gone off and come back on later.

Any other suggestions?... Car is perfectly drivable, I just don't want to
damage anything if it can be avoided.