I have 2013 Chevy suburban I had bad motor mount and transmission starting to slip so I changed the mount..and tranny still slipping. when starting up in the morning it will shift fine after 20 minutes of driving it will Start to slip I pull over turn truck off and back on it will start shifting fine again than ack up again after 5 minutes..what could it be tranny in its way out? I think it could be something stupid