What year is your accord?
When you say both Tach and speedo needles drop to zero and then bounce around, does the engine continue to run normally?
(note: what you read on the cluster is different than what the ECU reads from its sensor feeds)
Check that both battery terminals are clean and tight.
Check that the car's grounds (thermostat housing on engine, transmission, valve cover/head. and body) are clean and tight.
Use electrical contact cleaner to clean the connections to the dash cluster. (disconnect the connections and clean them)
My old 1991 CRX Si had a faulty ground connection to the cluster (too many previous owners; one of them screwed up the harness plug to the cluster; the ground pin in the connector plug was only connected by a few strands instead of the full wire; I pulled the pin, uncrimped its connection, added a 1" tail, then reconnected that to the ground with a small crimp connector). Sold the CRX Sept 2014. (too tricky getting it smogged and finding parts.)
take care,
ChrisS