Po308 code still comes up

My 2000 tundra 4.7l v8 with 223000 on it is misfiring. This truck has always ran like a champ. But it started running rough the other day and the check engine
light started flashing. I checked the codes and po308 came up. So I changed all the plugs and the coil pack at number 8 cylinder and there is no change. One minute it's smooth and the next minute running rough again. Any ideas?
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On Sat, 21 Nov 2015 22:18:01 +0000, Danny

Sounds like a bad injector??
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