i have seen this problem in a lot of mr2's if it is the front left you are most likely encountering athe same problem I am thinking of. For some reason the wiring for the spekers that runs throught the door boot seems to rot on a lot of mr2's. A siple fix would be to rewire the sreakers from source to speaker. Most of the time that is the best fix.
very common, happened to mine. here's the fix, make sure you connect everything right back together, i put my power mirror connector on wrong and thought i broke it but it was just plugged back in wrong. fix all the broken wires, they are probably all brittle, i yanked ones that werent brokent to check strength and fixed any that broke.