1990 Toyota 4runner HELP!

My 1990 Toyota 4runner will start and drive fine while cold…when it heats up to normal temperature it doesn’t shift. When i push on the gas is just revs and the car rolls? any idea what can be wrong?

I presume automatic.

Your first step is to check the automatic transmission fluid level.

I have…all the fluids seem to be fine…thats what i can’t seem to figure out whats wrong. and i dont have alot of money to put it into the shop…