My 91 Camaro gauges really let me down. Ran out of gas on 1/8 tank. Later found that the tach is reading double!! This is madness, seems like a dash replacement might fix it, or will I end up with the same thing?

unfortunately, the factory guages arent really reliable from what i`m told...but just to be sure, check all the grounds to the dash, and at the back of the heads on the motor...bad grounds can really wreak havoc...

http://www.thirdgen.org/techboard/electronics/357893-90-92-tachometer-fix.html?posted=1

read that to fix your tach.