I have an abf in my corrado with a longlife exhaust, its having a popping sound coming from exhaust every now and again. And when sitting inside the car I can feel that car vibration as if its misfiring.there are No idle issues though and runs great, just a slight misfire at idle. I Had put on diagnostic but no fault codes at all. Tried new spark plugs, ht leads, coil, lambda, oil, vac lines so dont know what is causing it. Anyone?