Rough Idle and P0401 Code

[TheEdgeofSanity]

hey guys,
since I got my malibu, it hasn't exactly had the smoothest idle. Recently, it seems like it has gotten worse, especially when the engine is warmed up and the car is in gear. I also have noticed a decline in city fuel economy, but no change on highway mileage.

the other night, my SES light came on for the first time ever and I took it immediately to auto zone. The car had a pending P0401 code which signifies an "EGR system fault". There was also a P0401 in the history.

Well, a new EGR is nearly $80 so I held off and was going to try to clean my existing one. In the mean time, the light has gone off by itself so does this mean whatever malfunction my EGR had has resolved itself?

Also, how common is it for the EGR system to become clogged? my car has 79K on it which to me signifies it should not have a bunch of carbon buildup. I kind of want to still remove the EGR to investigate but I'm afraid I will break something so if anybody has any pointers before I dive into it please let me know