Recently, after the weather got cold and after an exhaust redo (BBK l/t's w/ 1 3/4" primaries into a dr. gas x and flows.), my car has been sputtering after a certain point after i first start it up and drive it. It's fine, and then all of a sudden (about 5 minutes into driving it) i lose most of my power and if i give it too much gas, the whole car bucks and it makes what sounds like a small backfire, or several (depending on how much throttle i give it) that sources from the front/center of the car. I've already tried to reroute more air to vacuum because there is none coming from the dr. gas xpipe, but it has not helped. Also, when i start the car first thing every day, it starts, and just dies. I start it up again and its fine. Not sure if this has anything to do with it, but just makin sure. Any ideas? Thanks.