I've used the forum before to help diagnose and fix stuff,but this is my first post.
Anyway, starting last week, when I started my car up after sitting for a week while I was gone, it took a lot of power to back up,as if the brakes were on. After that, and while in drive it seemed to run normally, so I forgot about it. Yesterday, however, I started hearing what sounds like a high pressure air leak and it would dog down if/when I hit the gas above 30mph or if I tried really gunning it from start. It also lost all power when going up hills, slowing down to about 45 from the 55 I was going, even with the pedal to the medal.
Do you guys have any advise as to what it could be and how to fix it?
*Please note: I'm far from being car savy, so please explain any fixes in as plain a English as possible. Thanks!

 

Is there a check engine light on or have you seen one? If so, you should retrieve codes from computer.

While parked in the driveway, pop the hood and operate the throttle manually. You need to identify the noise you are hearing (vacuum leak?) and where it is coming from, as it is likely related to your symptoms. Do some sleuthing; it's step #1.

Good luck and keep us updated!