I have a 2005 Toyota Tundra with the 4.7V8 its also 4wd its got 327k miles on it and it started running bad and when I pulled the first fuel injector out I could see coolant on the injector and could smell coolant on the injector for cyl 3 but the rest of the injectors are dry of any coolant. But I dont see coolant on the oil dipstick and the coolant is not overfilling the overflow. Could a blown headgasket still leak coolant onto the fuel injectors? Ive never seen coolant on fuel injectors before Im hoping its as simple as the intake gasket.
My bet's that it is a head gasket, and it's relatively new/small (though it's not going to stay that way). Scotty has had success with head gasket sealer so it may be worth a try
https://www.youtube.com/watch?v=X0EdjDmfu8k
It's either a blown head gasket or a cracked cylinder head or block.