[gtmud]

Thinmints,
First, have you changed the oil regularly and kept with the same brand name and type? If so than I would leave the engine alone, doing the engine flush has been known to lead into more expensive repairs with higher milage engines. If you want though, I would look at flushing the coolant system. I work at a Ford garage, and we use a flush kit made by Wynn. Seems to work good, except for the occasional plugged up heater core.
The key is, if all is working well, tranny fluid is still red, coolant- green,and oil pressure still good. You should be fine. If regular maintenance has been done all along.