I replaced plugs about 20,000 miles ago with #2 coil pack. About 10,000 miles later the #6 pack went out. Yesterday after about another 10,000 miles #3 went out so I replaced the remaining packs for #1 #4 and #5 packs. I started to drive the vehicle to test it and got the p0304 and p2311 codes. Where do I look next to solve this?