2011 Prius IV Having Trouble Getting Air In / Breathing Can't Figure It Out

The miles and when the first EGR cleaning occurred.

 

Give all the credit to Mendel

I have a feeling that the preemptive parts cannon exploded in the barrel causing collateral damage.

About the only time a hybrid engine runs at idle after an initial two minute warmup is when the hybrid battery is discharged.

Aftermarket egr valves are a different design than oem and are known to stick open. An egr should have no flow at idle and will cause the engine to run rough if it is sticking. If it is significantly open the engine may stall.

Air leaks at the egr system gaskets or missing gaskets will also make it run rough.

Aftermarket egr valves for these cars are a bad idea. Luckily there are no aftermarket egr coolers so if you bought a new one it must be oem. Hopefully the new "cooler" was not simply an egr pipe.