I have a strange one that i had to deal with once. My o2 sensore wire has a ground shield around the wire. This shield is connected to ground near the ecm. My problem was from y mechanic replacing my o2 sensor and splicing the ground wire with the o2 wire. Hence dragging my o2 voltage down to ground making the ecm think its running lean, it then poured more gas in and was actually running ritch. When the engine starts up it waits fro the engine to warm up before pulling data from the o2 sensor which leads me to believe that it might have soemhting to do with your problem. Forgive me if this was already covered there was too many posts to read them all. When i was having this problem the car ran horrably, would stall at lights and would be unable to start again without waiting for all the extra fuel to drain out.

Another thing to check is your egr valve, if its leaking or opening up at the wrong time it can cause all kinds of wierd running problems. Try pushing on the plunger while the engine is acting up to see if it changes ur idle speed, it should pretty much stall the engine if u press the plunger up for too long.

HTH