cjhsa, your problem is almost definitely a short in the wire bundle from the battery (probably due to age, and moisture infiltration) that is intermittent; when it happens, the tach dies, and the presets are wiped out, and then, when it ceases to short (probably from the heat generated from the short drying it out) both return to normal.
[warning do NOT replace the instrument cluster, as the new one will be connected to the same wire bundle with the problem, and the expense will solve nothing.]
hey my problem is a little differnt my car when its running i hit the brakes and the signal lights come on. the headlights wont work at all but the fogs? what can i do to fix?