I have a 2009 Avalanche when I start from a stop normal accelerating it seems to stall around 10 mph and seems to be mostly fine after about 20 mph. It just started happening I took it to the shop and they hooked it up drove it around and said no breather problems or fuel problems. I live in Oklahoma and I thought it might be the heat getting to a weak fuel pump but they say it’s a torque converter. I do hear a pinging noise from under the engine that I thought might be a loose heat shield around the exhaust. So what do all of you think or has anyone had a similar problem?