Used to have a Jeep Compass myself, 2007 sport with the 2.4L and CVT automatic. Does she have the CVT or a manual trans? Not too sure how much has been changed since I had my Compass but the CVT is still the same far as I know and it has to have EXACTLY the correct amount of fluid in it and this change has to be done by the dealer since it takes a certain tool to measure it being as there is no dipstick lol. How long has she been having this problem? Dealership will say their hands are tied if they can't either, replicate the problem or the CEL is not on but if they've flashed the computer and there are no codes, it's tough to find a place to start trouble shooting. You might try a bottle of fuel injector cleaner in the event it may be a clogged injector or even bad fuel. You can also sign up for our Z site for Jeeps, www.jeepforumz.com
, some pretty knowledgeable folks over there as well but good luck and keep us posted!