Overheating dilemma....need input.

A simple home flush is to take the radiator off, turn it upside down, and flow water in the bottom hose, which reverses the normal flow. I have rigged up a garden hose w/ fitting so I can clamp to the lower hose and build up pressure. With rad. cap on, I block the upper port (now on ground) with my hand, build up pressure, and release to get a quick gush of water. Keep doing that. However, don't build too much pressure or you could rupture the radiator. Minimal risk, since the force on your hand blocking a 1.5" opening at 20 psig is 35 lbf.

You can find posts here where people use citric acid and such to clean their radiators and the before and after photos of the internals are amazing.