Cruising on the highway the car feels like its pulsing. Its not smooth. Ill be driving and ever few seconds it feels like it tugs forward a bit. Its no like a huge misfire or anything. Only happens when the cars warmed up. If I shut it down for a few mins and start it up it goes away for a bit. Also, when I punch it on the highway it dogs and doesnt do much of anything accept get loud. Coil, opti? someting else? Thanks.