About a month ago I started popping codes on my 2007 Chevy Avalanche (LT, 5.3 Vortec 5800 LMG Engine.) I did my research and foudn that, as suspected, I was getting a misfire on cyl. 7. Knowing that there are a host of problems that could contrinute, I dicided to eliminate the easiest one first, which was long over due anyway. I replaced the plugs and wires, as at 160,000 miles they had never been replaced previously. (shame on me, I know.) After replacing the plugs/wires and resetting the codes with my handy doodad, the misfire (rough idle, occasional engine jump, etc) was still present.....BUT NO ENGINE CODES OR LIGHTS? So now I'm wondering what to do. I hate to take it to the dealership and have them run off with my wallet, but I can't figure out what is wrong without an error code to eliminate it. I thought about disconnecting cyl 7 and seeing if the rough idle continued, but it's so random and slight that I'm afraid I won't be able to tell. A few details: Rough engine idle occurs after warming up. A cold engine runs nicely. A few other codes were presented at the same time, but I didn't write them down, so I can't recall exactly what they were. One had to do with the fuel vapor solenoid (P0443, P0446, etc.) I bought the solenoid itself and was ready to replace it, but since the code is gone now...I have no idea if it's still an issue. Can this cause a rough idle (i.e. misfire?) The other code was related to the P0307 but I can't recall what it was. Any thoughts, ideas, suggestions, etc?