2004 tarus wagon sel
tach dosen’t zero out when off (may settle while off)
one never knows where the gaauge will start or if it will jump
tach states higher thsn actual RPM’s when vehicle running
tach is currently reading off the gauge (like 8800 rpm’s)
doesn’t seem to be any real motor issues but still very discerning
Your gauge is defective. If you feel that you really need it to work, then replacement of the instrument cluster is the solution.
Just ignore the bad gauge.
IMHO the tach is only needed for diagnosing a problem or racing.