Drop the pan (you should do that anyway to get the sewing machine oil out of the tranny - not good for it at all) and manually pull the lower end of the cable where it hooks on the throttle valve to see if you can free it up. If you use a solvent, use dexron, which is just full of detergents. All this will cost you is some time and a pan gasket and some Mitsu tranny fluid.

Not responsible for advice not taken...