Optical sensor in the dizzy is your next suspect. If you have a friend with an old DSM datalogger you can test while cranking to see what the tach is sensing for a signal (the stock gauge isn't sensitive enough to diag). If it's all over the place or not registering, there is your fault.


1999 Montero SAS'd on Kings and stuff

1998 Montero trying to get a V8 Swapped