Hi there. How is everybody?

Monday i had a o2 sensor replaced on my wagon because the engine light came on, also the idling was going up and down at times. There were two or three different codes my mechanic said came up when they did a diagnostic.Sorry but i dont't have the codes on hand but i will post them when i get home. If i am at a stoplight, the car would be idling normal but sometimes feels as if it was going to shut off and the engine light would come on then go off.The car never would actually shut off just felt like it. This would only happen after the car is warmed up and i've been driving for a bit. i call myself looking for a vacuum leak somewhere but have not found one. How can one check for a vacuum leaks at home? Maybe i was not looking in the right places. My mechanic did say to unplug the cpu on the pass. side kick panel for about twenty minutes or so to see if it would reset itself. Anymore ideas on curing this ailment is as always appreciated. thx. B