2006 Tacoma air injection touble

I am getting codes for air injection valve stuck closed as well as rough idle and loss of power. Is it possible that the part is what’s causing these issues? My mechanic said he’s let me know once he found the parts but I haven’t heard back in a few days. Can anyone recommend where to find these parts other than oem?

I’m planning on having the engine rebuilt since it’s getting close to 300k any advise on how to go about it. Thanks in advance

 

4 cylinder?

 

Yes sir

 

On the V6 if the system throws a code the truck goes into limp mode and is barely drivable.

 

Price out a long or short block from Toyota. You may save money

 

What’s a long or short block? Guessing the engine? And what would the difference be