"He said the radiator is half boiling and half very cold."
That makes sense to me... my car is currently in the same boat, i need to replace the radiator at this point as a radiator cleaner and flush did next to nothin'.

After driving around, getting everything up to temperature, park the car and kill the engine. pop the hood, and reach your hand into and through the blades of the NON-MOVING fan and up against the back of the radiator. feel up and down against the metal fins, if parts of your radiator are clogged, you'll find there's areas that are quite cool, and the areas where the fluid is flowing nicely will be very warm, every bit as warm as the top radiator hose.

In my case, the top 4 inches of the radiator are warm, and the rest of the radiator is cold. this tells me that the radiator fluid is only flowing through a few of the top cross channels, and the rest of the radiator is clogged up. the flush i did yesterday only added another inch or so to the area that is dissipating the heat. so I'm ordering a radiator tonight. just need to find the cheapest place.
though i have not done so, I understand replacing a radiator is a piece of cake, as long as you get the right one!

good luck.
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