Cold start idle issue on 92 Accord

The car develops a symptom that when started cold, the first second the engine RPM goes to around 1700, which is fine, but then will drop to below 800 immediately for 2 seconds and the engine struggles a little, and then the RPM rise back to normal fast idle range and everything is fine. The car runs great except this problem, especially when it's cold outside (below 30).

Anyone seen this problem? How do you fix it?

My '95 does that after a cold night. It hasn't bothered me enough to look into it yet.

The timing of the sag is exactly concurrent with oil hitting the pump and starting to pressurize...it seems for some reason it doesn't compensate for that additional load on the motor as quickly as it should...so I'm wondering about my ISC motor...may be the start of it going bad...