rough running if car is restarted warm 86 5ktq

[blarson at Zeiss.com]

I was wondering if you guys could help me with some diagnostic issues.  My
86 5ktq misses when restarted with a warm engine, and has a low and erratic
idle when this is happening, then it runs good once it gets up highway
speed for the rest of the trip.  The car runs good when cold, but is a lot
harder to start once the temperature drops below 25 degrees F.
I am thinking of starting to chase this problem down by putting in a new o2
sensor, and going from there on the diagnosis, does anyone have any
suggestions?  The tune up is good on this car, no vaccuum leaks, good wot
switch.
I spent an hour in the archives, and did not find too much related
information, sorry if this has been beaten to death before.