I'm certain others will chime in and agree do not buy the $1500 part!
1) You can buy an aftermarket air injector pump for $140 or less on
ebay:
https://www.ebay.com/itm/Secondary-A...AAAOSwzixdU7Uo
2) The Relay Control Module which controls the air injector pump is the more likely cause of the problem, and it can cause unrelated problems like a no start. $119 on Amazon:
3) An air injection Check Valve can stop working. Available on
ebay $138:
https://www.ebay.com/itm/NEW-GENUINE...cAAOSwlahdZMPr
4) Her is a picture of the air injector on the front of the engine. There have been instances where cleaning the electrical connector contacts, and the grounding wire connector shown in the picture has solved the problem.