lx5.0

i just finished with making a block off plate for my egr because i thought that was the problem that was making my car act funny. It started when i installed my cold air intake when i start my car up in the mornings it will not start unless i give it some gas and the idle sucks once it goes on its own then when car gets warm idle smooths out. But then when i go out to take it for a cruise the car runs fine at a constant speed then all of a sudden it feels like if it pulls back, like it a bad sensor got triggered and you can also feel it like stuttering. This only happens at cruising speeds. Ive check for codes already and its just the emissions codes that show, i was thinking maybe it could be my IAC.