I recently had a rough idle and such when car is warm and fit into the common problem of having the egr valve clogged up.so I replaced the egr and coil's /plugs/ wires as well. The problem is the check engine light was still on (P0300) after all the new parts and still had the rough idle. Today I was heading home from work and noticed the check engine light went out and the idle was smoother at staying around 800 RPMS. I was excited !but then the same night heading to my girlfriends the check engine light came back on and the idle was rough but almost smoothed out a couple times. What is going on ??anybody have a slightest clue?

Much appreciated

 

Kinda the same problem here but with a p0303. Any modifications done or is the car stock?

 

Try changing the vtcs/Vic's/egr solenoids. Originally I had p0090/p2009. Few days past p0300 and another code popped up. After I changed the solenoids. Codes disappeared and car ran way smoother. Also clean your maf sensor and new plugs. When doing plugs make sure to put that connector grease on the end where it makes contact with the coil pack.

Hope this helps.