I have a 93 Accord EX Coupe. Tach will jump around, at idle or at speed. Engine RPM does not change, sometimes the engine will hesitate while in traffic. I can detect a slight miss at times. My daughter actually claims it stalled on her in traffic, but I have not be able to duplicate that, just the very erratic tach movement.
No codes, ECM cleared.

Checked all connectors
Replaced coil-no change
Replaced ICM in Distributor-appeared to get worse.(connectors all tight)
Replaced complete distributor(new)-would not run(yes the dist was in correct)
That really through me.
Reinstalled old dist, right back where I started.

The attached video shows exactly what I have, but even at idle

Let me know if you have any suggestions from here. Thanks

 

You may want to pull the cluster and look for any loose or damaged wiring. Check that all the grounds are attached with a clean tight connections. Inside the engien bay look for a blue single wire that has a connector that leads to nowhere. On 94-97 cars it is located near the fuse box on the right side, or left when facing the engine.


This is an image from a V6 accord so ignore the wire color that is noted. IIRC it is blue wire on F22 cars.
If you have a volte meter with a tachometer setting, or spend ~$25 bucks on a cheap Equus unit from the local autoparts store, you can tap into the Tach Test Port, and verify if it is the igntion system itself. Or simply something is wrong with the wiring or driver in the Tachometer.

My '95 Ex has a tach that reads lower than actual, progressively getting worse.

May just need to replace the tachometer. If the wiring is fine.

 

Did you ever get this fixed?

 

Yes. Replaced engine wiring loom. The problem was in the connector to distributor. The tabs in the connector that hold the female pin in place had broken off, connector was sliding and allowing a poor/intermittent connection. An option was to replace the connector on the loom, but to me it was easier to just replace entire loom. Loom is still available from Majestic Honda or there have been several used on EBAY.

 

If you check thread I posted the fix in November