My check engine light came on with a P0441 code. You can check the code by turning the key to the "ON" position quickly, three times. The code will display at the odometer. A P0441 code is triggered by a leak in the fuel vapor system. My truck also would idle irradically. Revving up and down. Then I noticed what appeared to be gas leaking from around the fuel tank opening. I replaced the fuel cap, but that didnt stop the problems. Then I examined the area around the fuel tank opening. I noticed that three brackets held the opening in place. One of the brackets, which are welded to the fuel tank, had created a very small hole. Apparently the vibration of riding over the years had created the hole. I sealed up the hole, then reset the CEL. You can reset the CEL by turning the key to the "ON" position, then disconnect the battery and then reconnect. Since I sealed the hole the CEL has not come back on and the truck has no problem idling. Finding a hole in the fuel lines can be very difficult, but that is most likely the reason for you getting the code and can also cause idling problems because it disturbs the oxygen content of the fuel.