Glad you got your Tach issue worked out. I had a Issue similar to yours last year, Tach needle would just jump all over the place..sometimes slow, sometimes fast. I tried 2 different Clusters and it did the same on both..tried a new igniter and it still did it. Got busy with work and Family and the Civic is not my Daily so I put the problem on the back burner so I still never have gotten to the bottom of what is causing my problem.

 

Do you have a multimeter that you could use at the test plug? Thats how I knew i was getting the right signal at least.