https://m.youtube.com/watch?v=nxVYUDjh-Ic
What he found should not have caused the cat to glow. That looks to be the fault of garbage engine management. A cracked throttle doesn't make a gas engine run lean any more than pressing the gas a little with your foot would. What someone else suggested was that the engine management may have been cutting spark in an attempt to limit idle speed. Not a lean condition. It is a little confusing that the oil cap thing happened as this would cause a lean condition but was reinstalled before it even got to the shop with the drivability issue so I doubt it was related