Will give it a look at on Monday as well as the vacuum hose going to the distributor AND the Vaporizor itself......Thank you for your input BB

The only oddball thing I can think of is the fuel hose between the mixer & regulator. I have had that hose cause me great grief with strange symptoms. I think it would be worth a look.

And by miss I mean hesitation/ stumble when you step on the pedal to about half throttle

I believe from what the customers told me that it does it cold or warm......the truck will idle fine....I don't believe it's a loss of spark,when I removed the air filter today and started it right back up it ran GREAT no miss when you stepped on the pedal I put it in tilt bypass and didn't miss any then either...And it was acting up just before I took out the filter.....
and it is just a single OHC thought it was dual but just looked at the PDF for it that I have on my iPad and it is just a single cam

Does the miss come on only when the engine is warm? I do agree the model J's anymore are junk, but I haven't had one do what you're describing. When it's missing,is it an electrical miss (lack of spark)?

Is a aluminum head with dual OHC......as for the head gasket not sure the reman head was put on about a year ago at the shop and it blew I guess a while back and customer sent it to shop to have new head gasket put on. The customer does their own " maintenance".....using that word LOOSELY....and noticed coolant in the oil I guess....after they received truck back it had this miss AGAIN......this has an IMPCO Model J reg that I installed in Feb 2012 and a VFF30 Lockoff....I'm thinking th model j is giving it fits as the ones we have been getting are crap,am leaning toward installing a COBRA as that is what I have been installing more of and hold up better. Forgot to mention also that about a year and a half ago the timing belt broke and I installed a new one....was jut curious if this is a interference engine and maybe a bad valve? Would think the shop would of caught it tho when they installed the reman head....... The distributor is a electronic pick up with a regular coil with external resistor(all of which has been replaced with in the last year....but STILL this miss hesitate keeps coming back.........

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