kevin- forgive my ignorance- the fe mazda- is that the one with the iron head, cam in block w/ pushrod tubes?

I'm thinking
1)- tune up parts faulty (I've never had luck with TVH tune up stuff)
2)- distributor faulty-(again- TVH not my favorite)
3)-intake manifold cracked or gasket failing
4)-PCV valve failing
5)- does this have an Algas fuel system? May want to convert to Impco
6)- does this have the remote distributor electronic control module? If so, I've had to relocate these onto the "door" of the engine compartment to keep them cooler.

Just some thoughts off the top of my head- hope it helps

In your opinion- what's happening w/ the headgasket- 2 within a year seems alittle excessive