Anyone having trouble with Torque Converter Clutch Shutter in their 2500 Avalanche? I bought mine used with 21000 miles on it and it runs great. The 8100 motor is strong. Back to the question. I have had it at the dealer several times, they can feel the shutter between 45 & 60 under slight load conditions. There checks says it has too much exhaust back pressure. Truck came with a flowmaster and dual exhaust, too loud for me, so I had a stock muffler and single exhaust put back on it. This did not help the problem though. I have mention to the dealer that the exhaust has nothing to do with it, but they will not replace the converter. Anyone else having this problem. Thanks.