Hi, I'm looking for some help with my transmission. I have the nv4500 in my truck and a week ago the truck while in 3rd gear would pop out of gear while under throttle mainly when I would get on it moderately hard. After that I began babying it not hammering throttle or anything. I got it home and checked the fluid level and found out it was low but not extremely low. I filled it with the recommended fluid and let it run a little bit and then didn't drive it all weekend. Now Monday morning after this weekend I was driving to school and third gear became unusable it will not stay in gear under any load at all. I'm unsure of what would be causing this any advice or ideas would be greatly appreciated.