P219A Air fuel ratio sensor

Severe rattling that goes away within a minute is typically a head gasket. Codes may or may not be present but are usually misfires on changing cylinders.

A Borescope inspection with a quality two view tool when cold with the radiator manually pressurized is often definitive. Traditional hg checks like leakdown, compression, coolant loss or combustion gas in coolant are not typically useful as these engines seal quickly when started.

 

If it's really happening randomly / sporadically, not consistently, there is also another issue it can be, nothing to do with the head gasket; it can be water that condenses in small passages of the intake manifold while the engine sits in the cold, as was addressed in this TSB. Seems more likely to happen if the last use of the car, before sitting in the cold, was brief and it didn't fully warm up.

For a while, Toyota offered a revised intake manifold where those passages were a funnier shape less likely to spurt the water out, but that didn't seem like a silver bullet, and even with the unrevised manifold it seems you can mostly avoid it just by making an effort not to have brief, non-warmed-up uses of the car before letting it sit in cold weather.

 

I have seen many people throw thousands away on plugs, coils, injectors and egrs without results.