Ford Guru

My cousin has the same issue with her 2015 Silverado with a 4.3L and a 6L80E transmission. I dropped the transmission pan. Changed all the solenoid membranes on the TEHCM and replaced the fluid and filter. I even replaced the manual detect plunger. Shifting is much improved. But she still gets the erratic idle and it clunks into 1st gear. But only sometimes. My synopsis is that it has something to do with the torque converter lockout. Unfortunately this part is out of stock with no timeframe on future availability. They are in a class action lawsuit over these ****** transmissions currently and all parts are being thrown at warranty claims. GM really built a terrible transmission. And they know it.