[MR2] Tach issues

[casorlalouis at yahoo.com]

Does anyone know what could be the cause of my 91 MKII turbo stock tach to be sticking from idle until abt 2000 rpm? Once in a while(very rare) it reads accurately and doesn't pop up and down. Kinda appears stuck until it hits 2000. And when I turn off the engine it stays around 800 to 1000 rpm. 
Anyone have any ideas?

Mahalo from Hawaii
Lou 
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