Here is what happened...I had a CEL for the front O2 sensor on my 98 V70R. While I was investigating how to reach the sensor to replace it I cracked the PCV hose near the turbo end. So I had to order that, I watched a few videos on how to do it and seemed pretty straight forward except for it being a lot of work. I figured while I was in there I would clean up stuff, replaced some old vacuum lines that I hadn't already done in the past. I also replaced my cbv with a forge unit I had sitting around that I never had installed because its a pita. So after all parts came in I put everything back together, everything went back together normal, no leftover parts or bolts But now when I start it up, it jumps to about 4k rpm for a couple seconds then drops down until it shuts off, takes about 3-4 seconds. It does the same thing every time, I don't even step on the gas pedal, it just revs all by itself, and starts right up ever time. As far as I can tell all vacuum lines are back where they are supposed to be and everything plugged back in. I am going to borrow a neighbors car to do a comparison. In the meantime...any suggestions on what it could be, what would make it rev up and then die?