I have a 2005 sti with Turbo back Espilir 3" exhaust , K&N Typhoon intake , Larger top mount intercooler , and Cobb Accesport. the car is set up as stage 2. I have had the car for a year now and have been chasing this issue down ever since. i have had the car to three different dealers an none of them can help. I have no cels on dash and the accesport verifies no bad codes on the car. The car runs pretty much perfect when driven for the first time that day. I can let the engine warm to running temp and leave my house and about 15 min into my drive i'll start to get pulsing at a constant speed whith small flutter in rpm. I get grabbing and hitting in my drivetrain along with it. In town i can free roll in neautral and hear and feel grabbing in the rear half of the car. At this point ive checked plugs ect. and the shops have said nothing is wrong with my drivetrain. I dont know if its motor or drivetrain at this point. I even had a few occasions where backing out of somewhere the car jumps from manual DCCD to lock and feels like im dragging my rear wheels. Any ideas? Please help if you can i love my car but to my wit's end. You only feel as good as your car runs right?