1998 Ford Ranger Possible Transminssion troubles

Transmission problem
1998 Ford Ranger V6 Two Wheel Drive Automatic 82,000 miles

I just recently got my ford ranger fluids replaced after it sat idle for a year in storage. The place I recieved the services at said my Ball joints on the truck are starting to go bad so when I intially felt small kicks as I drove over bumps I figured it was time to change them. But before I could go do that I had came to a stop and tried to go after stopping and the truck just would rev up and not move in drive I changed gears and put it it park a couple times before it kicked hard and went. I checked the fluids it has them but now I am wondering if the transmission is going bad.