Alright so my 98 gt is misfiring pretty badly but it seems to go away once I hit about 2200 rpms so on the highway in 5th it is unbearable and in the city in 4th it is awful. It is really annoying and just sucks. It didn't do this as much as 2 weeks ago but then it sat because I had knee surgery and couldn't drive it. Anyways I took it to my buddy and he looked up the codes but I wanted to get your guys opinions. I have new coil packs, new wires and new spark plugs that I put in to try to fix the problem but it didn't work. The codes are P1150, P0155, P1152, P0304, P0308. Also, It is straightpiped with no cats but the rear o2s are in the pipe and connected. Any help would be greatly appreciated.