Each time I wash my car I spray the cold engine with simple green solution. You can use any cleaner that is friendly to wiring and rubber. Then I start the engine and hose it off with low pressure water. Avoid the distributor but, anything else is fair game.

If your car starts to miss, you have found your vacume leak or misconnection.

Spray the water over the injectors and vacume hoses also. If you do this regularly, you won't ever need a steam cleaning.

by-the-way, steam cleaning is really not good for your engine or components.