transmission slippage

if it is full of fluid and fluid is not discolored like dark brown or black it can be any of those but normally on warm/hot cars it is more of a seal probably getting fluid past it. best to check with a transmission guy on this though.

I'm sorry to report that I don't know a tranny guy I can trust as the blanket answer is "your transmission is bad give me a thousand or two and I'll fix it .
I live in miami so it is never cold , but obviously the more I drive it the hotter it gets ,,,so a friend suggested he once had a similar problem and his was a solonoid. Another said it might just be the filter occasionally clogging. When you say "Seal getting fluid past it" ? What seal are we talking about ? I recently replaced one that was leaking, but the problem didn't go away.
Are you suggesting it might have a slight leak when the heat and pressure builds?

the seal i'm talking about is the seal that works the accumulator or clutch which ever application goes to the gear you have the problem with. If the solenoid was bad it wouldn't shift so rule that out. The accumulator operates a band