Could be all of the above.
First- with the engine hot idling in neutral pull the tranny dip stick and check the level. Also look at the oil is it a nice red or dark almost brown, smell it, is it burnt.
Second- Check that the kickdown linkage is adjusted properly, kickdown lever on tranny should be all the way forward at the same time carb is wide open.
Third- if everything looks and smells good drop the pan and check for everything from bronze to steel to rubber bits fileings and drop the filter and make sure its clean.
Let us know what you find.