2001 malibu problems

Hello Guys:

my wife got gas in her 2001 malibu today and shortly after driving down the road her check engine light came on, she thought maybe she forgot to turn the gas cap the required 3-4 turns, I had to take the car to get the oil changed and the guy put it on the machine and the code stated EGR or ERG valve code granted sometimes the car kinda skips going up steep hills until you give it more gas and you have no more problem,mileage is about 119,000 what do you guys think , does EGR or ERG need to be replaced ,cleaned out or maybe a gas system cleaning, which is $65.00 dollars where I get my oil changed not really knowing if it will work or not

Thanks copdills