help !

[roadking]

started my truck today and as soon as it started it had a miss and low power(edge disconeced & smarty on stock ) no smoke , yes the truck seemed to be starting a little hard the last few days took it to ******* checked it with the computer said no codes #'5&6 cylinders were weak , #6 was 180% the rest were 250 % whats wrong is it a bad injector? or a blowen head gasket between 5 & 6 no oil in water ,or water in oil help only help!:{