My '86 with the 2.8 multipoint fuel injection is very unstable for about
the first 30 seconds or so after startup - The idle pendulums wildly
between almost stalling and 2000+ RPM. Then after anywhere from 30 seconds
to a minute or so, it settles down. During this instability, the exhaust
reeks of partially burned gas.

Only happens when I start the car after it has been sitting for at least 4
hours. No codes on the OBD-I.

I'm no "expert", but my own best guess is that I probably have one or more
fuel injectors and/or cold start valve that are leaking after I shut off,
and after 4 hours enough fuel has built up in the cylinder(s) to drive the
ECM wild when I start.

Is this a plausible theory ? Or is there something else I should consider
before I replace all the injectors and the cold start valve ?