Ok, I've just fitted an FMF Powercore 4 to my 98' XR6, ground header welds, snorkel removed and re-jetted with a 155/68 with the needle in the 4th clip position. Initial tests all pretty good although may have to go smaller on the pilot jet, just took it for a proper test ride, ran great for 5 mins then just died in the arse. Engine was still running but only at a slightly higher idle, no throttle response whatsoever but barely idled all the way home, idle adjustment screw made no effect either way, full choke on and off had no effect, and throttle cable seems to be moving all the right bits. What can it be? have i stuffed something in the carb or have I done something more sinister to the motor, some help please?