308 Sputtering and Tach loss

I've been convalescing an injured right shoulder, not able to shift for 6 weeks and need to get my 308 to the Greenwich show tomorrow. So I decided to teach the wife how to drive it. Natch, she shifts too slow and I had to keep telling her to keep it between 4 and 7 K on the tach. On the way home from the first lessons (all told about 5 - 10 miles) the car seriously starts missing and the tach pops down to zero or 3K intermittently.

I should add that it has 450 miles since a complete major - all new plugs wires etc. And that I've bucked washed it about 4 times in the past few weeks to detail it for the concours. The only driving was in and out of the garage with plenty of warming up.

After her driving, I took it out (with her shifting on my commands , Second - now!" "Second - locked!") and couldn't get the problem to repeat by running the same route in my usuall aggressive style (sans fast shifting). THe missing only happened once, briefly on the way back. Didn't repeat.

I remember seeing a recent post about fouled plugs and someone saying that the drop in tach was the sign of a distributor failing. True? If so, which, how, how to fix. Gotta get to Greenwich tomoorow moring. all quick help gratefully welcome.

The Q