Re: Speedometer an Tachometer reading incorrectly
Both speedo and tacho signal come from the PCM via the PCI data bus. So it could be that the PCM is sending a wrong signal, or the instrument cluster electronics is misreading the signal. Not sure if the instrument test will reveil anything, but its worth a try:
With ignition in off, push the odometer reset knob and while holding it, switch ignition in run. Now the self test will start, all indicator lights come on, but also the instruments should go to full scale and than back to normal indication. Odometer will count 0000000, 111111111, 2222222222 etc.
Do the speedo and tacho go to full scale and return to 0 during this test? (As soon as the test starts, you can release the odometer reset knob).