I bet he removed the butterfly valve and cleaned it, if you do that and do not get it back in place just right it can stick a bit, I know because when I cleaned mine I tested it as lot as I was putting it back, and I had to adjust the butterfly valve twice to get it not to stick.
If that is the problem you may want to take the throttle body back off, and loosen the two screws on the valve just a little, then adjust the valve a bit, then tighten it, then by hand goose the throttle a bit to get it to open the valve, do so till it does not stick at all.
You could do this without taking the TB back off, just do not loosen the screws much, and be careful tightening them, their heads round out easily.
I'd try to do that before trying to replace it.
2006 Pontiac Grand Prix GT with SC
1996 Buick Park Ave NA