Hello Im new to HP Tuners , I have a 2016 Silverado 1500 5.3 , I just put long tube headers on it and under load it runs awful sounds like its misfiring and puttering . All Connections are good , have no clue where to start , Im new to all this . It idles fine but once you get going it doesnt like it at all , anything helps ! I do have a cold air intake but I had that prior to this