[Jeff Lee]

Turned out the fault code for distributor was actually the spark plug was bad, somehow it lost the electrode. Not the ground strap, the electrode. That explained that problem.
Apparently the plug was loose also. That caused some carbon build up around the threads. So the mechanic tried to tighten the plug and felt something wasn't right (this was Sunday afternoon). So Monday morning he consulted the TSM on spark plug r&R (imagine a TSM on R&R spark plugs!) which I also found online Sunday night.
Engine should be warm, not hot.
spray Ford solvent down the spark plug tube.
Let soak.
Loosen spark plug 1/4 turn.
spray more solvent.
Let soak.
Lather, rinse, repeat...
Once he got the plug out he saw the plugs were intact. Plug replaced. Parts and labor were free under warranty from the shop.

This has been a very good vehicle as it has not cost me any money except maintenance and wear items for almost 115K miles. I change the oil every 5K with synthetic and have followed all the prescribed maintenance intervals. I just spent about $1500 on all the air-ride but if this was a standard suspension vehicle I would be on my second set of shocks by now (which would still be cheaper than air-ride). The left door regulator went out a few months ago (on our E-150 also, same week!). It still has the original trans and rear end which I'm not confident I could say about a 1/2 ton GM product with 115K on it (and I'm not the easiest guy out there). I consistently get around 16 MPG in city / freeway driving, rarely dips into the 15 MPG zone and if all freeway would be 17-18 MPG and that's with 3.73's.
I do not like the "tappet" noise but everything I've researched says it's an inherent problem (why?). I wonder if that is also an issue on all Ford modular engines. My 5.4L 2V E-150 with 100K on it doesn't have that issue and I don't hear it on every Mustang out there.

FYI - my research on the heli-coil fixes is be careful the insert is the same material as the cylinder head. Some are stainless and are not the same heat exchange and can cause grounding problems with thermal expansion differences?