I have changed the trans fluid and filter, I.

I have changed the trans fluid and filter, I used the correct pentrosin fluid (not cheap) @ approx 8qrts, followed all filling instructions. My problem is this, the car will go through the gears just fine until it seems to get warm and then will not come out of 1st or second gear. If I come to a stop and shut the car off and then continue to go it will shift correct again, but when I come to a stop and then go again, it will not shift. There is a clicking noise when I start the car and seems to stop when I apply the brakes (not sure if related) sometimes it goes away. I'm at my wits end about the issue and don't have the funds to take to a dealership. Any and all help would be greatly appreciated. Thanks