My wife's 03 GC, had a spurt of bad behavior this afternoon. She was merging on the freeway and it began to bog and almost stalled when she about hit 70. She pulled off and it idled normal but the engine light was flashing. She called me at work and I told her to turn it off and restart it, from there it ran fine but instead of flashing the engine light just stayed on. I had her check her codes and it came up with a P0304, I couldn't find the trouble code list but thanks to a previous post and ezflip I discovered it was a #4 cyl. misfire. I don't really know what could cause this and I was hoping someone on here would have some prior knowledge that might help me out. Any help or advice would be greatly appreciated. Thanks ahead of time.