Hi, I just bought my first mustang,is a 2002 automatic transmission v6. It run great at first but now I’m having issues with it. The car starts really good and takes off perfectly goes into 2nd and 3rd no problem but once it reaches 40mph I loose all power and I have to bring the car all the way down to basically 0 mph to get it back going. It runs good as long as I keep it under 40mph. Not sure if it’s a transmission problem I just don’t want to rush into replacing it. I already chance all the fluids and even replaced the filter and transmission pan.. any advice would be very helpful.... thank you