200T dont start when cold

[Denis]

Car: 200T 1989 automatic none quattro.

I Noticed too major problems:

1) Hard to start when warm or hot.
- Each time i try to start , the battery seams to go to the floor very easily
-After 5 start the battery is dead 
- it does that even with a new battery

Things need to check :
- Big red wire splice under the passager floor, to the starter...
-See if the starter is good enought,,, i have a spare unit.

2) Does not start when cold.

What i tried ?
Add ether before start it. It start hardly but start.
Retrieved fault code. 
2312: coolant temperature sensor.
I simulated the sensor with a potentiometer (10k) and resistor (100Ohm) 80ohm when hot, 6k when cold (SJM) (i dont have one right now ,, so )
It s start better but most of the time it does not start when very cold.

I unplugged the battery to reset the fault code but it still there.

The pot on the trottle is very oxided. 
Cleaned it, better idling now but still dont start when very cold (-15 to -30C)

I ll follow the Bentley procedure for cold start enrichment.

Ðenis