Update:

I just intstalled new overvoltage relay. Everything was perfect for the first 1.5 mins or so.

After the tach went dead again and the car started running at lower idle speed.

WTF is going on.

My best guess right now is that this has something to do with the glow plugs and the glow plug system . It seems like after the glow time was over the car started running like crap again.

One thing to note is that at least the ABS light is off and ABS does work.

Damn it Im slightly pissed off