I saw a similar post on here about a 2004 but I have a 1996 and the heat doesn't work at all. Fluid level is ok. Thermostat is ok. I'm guessing heater core? What do you think?
Also, my tach bounces around. I have an automatic and sometimes it works and other times it bounces or goes to zero. Gauge problem?

...Guess I should have checked the similar posts first...learned my lesson.

 

what was the fix?

 

The tach gets its signal from the ignition coil, even though the engine is running fine and not misfiring, the wire to the tach can still be the problem in the coil so dont rule out a bad coil and itw wiring to the tach along with your tach indicator diagnosis.