Tranny making clicking sound when in reverse or low idle

When I put the car in reverse or all the way down to first gear. The transmission starts making a ticking sound. Almost like a small peice of metal pinging up against another metal surface. As well when I go down the road doing about 70 and if i floor it to pass someone. Its like the transmission cant make up its mind . It downshifts to 2nd and then back to drive and this will continuously happen until I release the accelerator. It's not good whatever it is. By the way its a 700R4 for a 91 camaro rs. What could this be ? I would like to catch the problem before it grows to something more catastrophic.

Thanks,
Chris

Maybe your pump is taking a ****. Low and 2nd have the highest pressures and if it keeps shifting when in 2nd it might be because there is not enough pressure. Or time for a fluid change and flush. Filter plugged??? Or if it is beyond a change its time for a rebuild

Yea I had a feeling if I change the filter and change the fluid in it that if it does not take care of it. That it was the pump going bad in it. I really hope not. My 91 is the only car I have to drive to college every day which is about 100+ miles a day.