Aside of other issues I have had in the short time I have had the 09' Acadia, I have had some serious Air/fuel issues for the last month. Luckily/or unfortunately, I am pretty mechanically inclined and have the know how to troubleshoot and repair items myself.

I had just got done driving 1500 miles from Denver to PA, and then another 800 miles to MA and back, when half way back from MA my engine light came on and started flashing. An engine light in general is a concern, but when it is flashing at you.. there is a serious issue going on; i had some misfiring, the car had no power, bogging, sluggish and shaky at times.

Got it home, performed a tune up, to check out everything, and noticed oil on my 1,3 & 5 plugs. I ended up having to replace the cam cover gasket, both (2) rear cam position sensors, 3 new (1,3 & 5) tube seals, coils for the effected 3 and now just ordered a new throttle body, since GM decided that just having a single TPS wasn't enough, so instead of a $20 throttle position sensor (TPS).. you have to pay $200 for the throttle body, with a build in TPS!!!

I have looked and tested the vacuum line(s), with no obvious leak, and have put cleaner treatment in the gas and oil for good measure. It is running better, but still have the flashing engine light, even with resetting the system, some misfiring and still have the sluggish behavior. I will see what come off replacing the throttle body.