I have a 2012 Sierra with 5.3 with TSP 216/220 low lift cam. I did not have the TCM tuned when I had the mail order tune done. I have issues with sluggish shifts, surging at stop signs and lights, it idles a little high when in gear while on the brakes, also need to bring up shift points. I am very new at HP Tuners and need a little guidance where to start.