Good day everyone, I have a 2006 Charger R/T 5.7L automatic with 168K, I did a LH and RH head gasket replacement. Engine runs good but when I shift to D or R the car goes into gear and within 2 seconds it kicks it back into neutral, I have no codes present on either PCM, TCM, ABS. I didn't lose any trans fluid when I did the work. Fluid looks good, doesn't smell burnt, checked all my grounds, all have good continuity, checked trans connector, no bent pins or corrosion on it. Any clues? Vehicle drove good before I did the work!