Engine shuttering

I was driving my V6 Tacoma on the highway when all of a sudden the engine started vibrating . I know it's the engine because it vibrates at idle and at all speeds. This happened out of the blue, and wasn't gradual. The engine has 315,000 miles and has no check engine lights. Any thoughts ? Head gasket? I don't think it's a misfire because there is no check engine light.

 

there has to be a ceertain number of misfires before the CEL is illuminated... just wait.

 

Does it feel less powerful? Check your motor mounts and your tranny mount.

 

I feel like it's misfiring, a motor mount or tranny mount wouldn't just start out of the blue, it would be gradual, like a carrier bearing

 

Check your coil packs. Unplug one at a time. If you unplug one and the engine doesn't start missing worse, then you found it.

 

Solved: It was a bad spark plug wire.

 

coil pack is what it sounds like

 

Well it was the wire running from the coil pack to the other cylinder, it had apparently blown and was ground/arcing to the engine