I am having cold start/idle issues with my 85 190e (2.3 8V). I have tried running the car with and without the cold start valve plugged in. No change in startability, but seems to run better once started when the valve is UNPLUGGED. Idles very high either way (1600), but now the car does not stall when out in gear Seems as though this circuit is not functioning well.

I have been advised that perhaps I need an ECU. How much does an ECU cost?