Does anyone think it is the radiator besides me?

Wellllll, sounds like to me, just what your radiator guy already said and what others have said here.

The dang radiator is getting clogged by crud, scale, rust, debris percolating out of the engine.

When I was a kid, I had this happen plenty of times on my old Olds engines cause they were used or just rusty inside which were probably run with water some time in their life.

I would spend all day flushing and soaking a radiator in muratic acid only to have it clog up in a few days or weeks again.

So, I put in a screen!

I used a new screen over the upper radiator fluid inlet every few weeks the entire time I had the car. I would cone it into the rad if I was feeling motivated so it would have more filtering surface area and catch more crap. It always had plenty of crap on it.

There was a company called ganofilter or something that had a nice clear inline radiator hose filter. It looks like their website is down.

Here is another screen and pot type that looks promising from a Texas company:

http://www.tefba.com/

Seriously, the diesel truck guys are using something similar to a screw on fuel filter in a limited bypass arrangement to super clean their coolant because of debris from casting sand and other crap.

If you want to get fancy, you could also install a bypass filter in your heater hose so that the fine muck is filtered out. But the screen will trap any radiator blocking particles so you can remove them periodically.