Car started giving P0170 codes (daily for the past 3-days) and P0304 code only once 2-days ago). The codes were thrown only while running/stuck in traffic while the car was idling. Other symptoms were idle dipping to 5-700rpm every once in a while. Finally this morning I had enough and popped up the hood while the car was still running. There was a slight leak noise coming from the infold manifold area. Closer inspection revealed air leak from the fuel injector on cylinder no4 - the seal gave up the ghost. 10 minutes later after we changed the seal car is running perfect.