Honda: My 94 Isuzu bighorn wont move, Isuzu, transmission

Question
With my 94 isuzu bighorn auto when you put it into any gear the engine sound will change like it usually dose but the car wont move. Sometimes it will move a few meters but if you rev it will stop the engine wont stop but the car will just rev like you are in neutral. This problem has slowly started like when you first turn the car on it didn't used to change gear properly then it turned to when the engine got hot the car would stop moving and you would have to wait for the engine to cool down, and then it moved on to whenever you let go of the revs it would stop and now its at this. Could it be a belt or something, I've checked the shaft and transmission fluid and the gearbox seems alright from my point of view although i don't know much,I know you arnt specialized in isuzu but can you please try to help?

Answer
What you are describing is the transmission pump starves for fluid once the vehicle is warm. If you can drop the transmission pan and change the filter it may correct the flow of fluid. The problem with that would be whatever caused the clogged filter. In other words, the filter is most likely clogged with transmission clutch material or metal particles.