I have a 2002 tundra 4.7 with 113,000 miles. Has been running perfect. now i get missfires after the engine warms up sometimes. Ran premium gas with lots of dry gas thinking it was fuel. but no change. if it was a coil wouldnt it keep on misfireing all the time? Coded are p0300,p0301,p0303,p0304. radom missfire condition. Also might seem weird but i am getting a groaning sound also. Kinda sounds like a wheel bearing going bad. I read that someone else had this problem so i figured i post that too. It almost seems now that i think of it i started having all these problems after I changed my fuel filter. Might change again. gonna put new plugs in today. Any suggetions would be great.