Rough Idle & ck engine light coking on

does the ck eng lt flash? if so, you may be damaging your cats. you don't say eng type. if its a 4 cyl try removing the oil cap with the engine running, if its impossible you may need a new cyclone breather or worst case a whole valve cover. any eng: add some fuel system cleaner and make sure the throttle valve is clean for best performance. get the fault codes read to see for sure. misfire, idle speed and false air faults will accompany that breather thing.

An oil change will not fix this problem. The check engine light means it's emissions control system related (see this article: http://repairpal.com/check-engine-light). You'll need to get a diagnostic tech to pull the trouble codes and identify the underlying problem that needs to be repaired. I recommend visiting a good shop. Remember that some emissions components carry extended manufacturer warranties.