Engine Miss, sorta?
 

Here is my dilema. Sitting at idle, every once in a while I get a weird "miss". A miss is the best I can describe it as anyway. I notice a slight dip in rpm's and a slight shock to the car, almost like an on/off throttle with blown motor mounts. This happens almost everytime I drive the car, maybe once or twice each time. I notice it when the car is both cold and warm. I cant figure it out. Is there something I should check or adjust. I have replaced the fuel filter, O2 sensor, plugs, and plug wires. My only mods are a Bonez downpipe. One thing I can think of is that the previous owner got the ECU recall but never had it performed. It is the recall to do with idle falling during deceleration. Although not directly related to the problem I mentioned, it may have something to do with it. Any thoughts.

At idle the air fuel mixture is critical. Most likely you have a vacuum line leaking diluting the mixture. I don't think its ECU related. Just my thoughts.