Ricky touched on this earlier on and yes in the lower tin was fitted on back to front and the air was blasting against the firewall therefore not clearing away towards the back of the engine compartment rear door
sounds like you got away with incorectly/missing tin and was saved by j tubes just like me! mr zed rescued mine too with donation of parts.
Good job you got to the problems soon then before it did even more damage , my engine did not have any flaps it was just all ways open and was missing a few important bits of tin wear