2005 Nissan Sentra Starting idle

I have had a problem starting the engine lately especially in cold weather. Once the engine starts, it will idle rough and then smooth out as if there is no problem. I have used a troubleshooting diagnostic sensor (small unit that plugs in underneath the steering column) from a local parts store (Autozone) that gave a cylinder misfire reading. Since then, I have replaced the battery, which really needed replacing, and replaced the spark plugs to see if my problem was a faulty one to no avail. I also inspected the sparkplug wiresets thinking that there could be some arcing from the wires but there seems to not be any damage at all. I have also looked into another troubleshooting page that said the problem could be the idle stop solenoid but I don't know where it is on the engine and if it could actually be called something else by Nissan called the EGRC solenoid valve. Anyways, like I said, the problem only exists at startup and right after the engine starts (sometimes hard), there doesn't seem to be any other problems that I notice except that the check engine light is intermittent going off and back on when the engine thinks the problem is corrected. Thank You