1992 Mitsubishi 3000GT Engine

Head to the Chrysler dealer's parts department for some Engine Degreaser. It's green and looks just like antifreeze but it's thicker. It's extremely important to not pour it onto the engine. It only works if it's sprayed or misted on. Let it sit for about ten minutes, preferably on a warm engine, then wash it off with a garden hose or self-car-wash pressure washer. To be safe, let the engine dry all day before trying to start it in case water got pushed into the spark plug wires.

If the degreaser is only available in five-gallon pails, you can find other engine cleaners at auto parts store. They won't be as effective but two washes will do a good job. Other car dealers will have products similar to the Chrysler stuff. I just use that because I know it works well.