i picked up an 83 zx-gll model [t-tops, leather, digital dash, no turbo] for my wife. the digital dash is driving me nuts. i have seen the temp gauge work many times and the tach only 2x. i took out the instrument cluster, nothing appears to be wrong, i have also checked wiring at the tach, etc. anyone have any ideas or similar experience in solving the problem. i also have a strange exhaust-like sound under deceleration. it's like a valve opens under deceleration which sounds like an exhaust note-but it doesn't change in pitch like when an engine winds down. it stays constant until about [i'm guessing cause the tach is inop] 2,000rpm. help!

david