You seem right that it is not a mechanical issue. The computer is out of
loop each time the engine is started.After a minute or so,it reconnects
itself with several sensors.Does this same ,out of loop thing ,till the
engine gets warmed up.Then it goes closed loop,and your problems begin.It
is probly one of these sensors. You can unplug the oxygen sensor and drive
just fine. See if it is this sensor.Possiably your throttle switch is out
of adjustment.How many miles on the engine accessories?Water temp 2 switch
is a very  popular suspect.