I need help guys. I have 04 Silverado 5.3, bbk 80mm tb, underdrive pulleys, gm lsa cam 226/236 525/525 110lsa, 8.5 msd wires, tr6 plugs, 1 3/4 long tubes 3" y-pipe, 3" exhaust into magnaflow race series muffler, electric cutout, vette servo, 3200 circle d stall. Truck has been running fine. Recently started surging during braking slowing down. Surging to the point I am shutting down at red lights and pulling into parking lots. Thought vacuum leak was culprit but after pulling off and checking seems to be fine. Torqued everything back down. I am lost any advice would be welcome before I drive this thing into light pole.