If it has a clean red ATF fluid and still causing these symptoms, there is a chance the transmission might be failing. If there is some mechanic who can check the live datas and see if the transmission is overheating. If that’s okay then replace transmission fluid and filter once to make sure you are putting in the right fluid. Then drive it for a while and see if the problem changes. If not then it could be a transmission problem but get it checked with a transmission specialist.