I left my car untouched for an entire weekend. When I got back in and took off, something wasn't right. Seems like it just fell on its face after 4k. Usually it'll accelerate up to 6, 6.5k. My check engine has been on for almost a couple years and i have replaced both O2 sensors and changed out the plugs. Still not much better, although I can feel a very minimal increase in performance. I can hear the turbo working just fine. There is still something holding it back and I'm wondering if it's the cat converter. Any thoughts?