What is wrong with tachometer worked erratically then stopped altogether /

https://www.clubarmada.com/threads/erratic-tachometer.17405/
This thread has several suggestions from a failing battery to bad grounds or BCM problems.

More than likely the tachometer is defective, the little motor that moves the needle is failing, this is called the "Stepper Motor" The cluster can be repaired, check online for repair sites, cost around $200.00 US

Tachometer / Speedometer Problems: - Ford Explorer and Ranger ...

www.explorerforum.com > ... > Under the Hood

Jul 31, 2006 - 13 posts - ‎11 authors
Tachometer / Speedometer Problems: Under the Hood. ... upon restat the speedo goesto (is driven to) zero, the tach goes to ... 88 89 93 95 96 Aerostars ... in cold weather it seems to stick. but once the truck's interior warms up, .... 1995 Ford Explorer 4.0Automatic My Tach Quit Working And So Did My ... 5R55S harsh shifting; bump engaging reverse;
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1999 Ford Explorer , Erratic RPM Problem - YouTube

You have a engine RPM sensor that is not working correctly. Computer thinks you have push gas pedal to the floor and is providing that type of shift. It may be the sensor attached to your gas pedal has worn out.

One thing to check could possibly be a bad altanator which could cause the iggnition to run rough and make gauges act funny.

yes it could be

there are two wire beside the injection pump,,,, i think face the injection punp it is leftside... that's the wire sensore to the tachometer

You will find the Jaguar to be more problems, usually. MB will have less problems than the BMW.

It probably ran the alternator too and without it the battery ran down so the engine went dead without any power.

try fuel injector cleaner in your next fuel fill. sounds lke your injectors are dirty