Hey Early, haven't seen or heard from you in a long while. You still truck'in?
Foaming coolant can be bad anti freeze that's either way too old or contaminated; and maybe a really fouled or sludged system. Sometimes anti freeze types can be accidently mixed and boy that makes for problems. I bought a car where the former owner's boyfriend topped it off with DexCool when it still had some of the green stuff in it. What a mess that was to clean up.
Another could be air coming in through a leaky water pump seal. If you can, or by taking it to someone with a pressurizing tool, pressurize the system when cold. Use no more than 12-14 psi. Look for leaks while focusing on and around the water pump spit hole near the pulley shaft. A good UV light can help show up any leaking anti freeze.