I'm having a couple of issues that may be connected. 89 - 300e M103, Cal car - ck engine light on - when pressing the button the diagnostic connection it will blink back four, and the only thing I've found on codes shows only four codes 1-OK 2-Speed sensor 3- Coolant temp sensor, and 4-ELR control unit or idle speed control system. I assume this means the valve. The idle speed is 1000 when cold and the 1500 when warm. I've been told that when the idle speed control valve fails, 1500 is where it goes to, but I hate to just through parts at it. So 1- is there a way to test the valve or is the code four the tell?

The other issue that may be related to the first is that when cold the system seems like it's loaded up and has no power. I can tend to overcome this by forcing shifts at about 3000 and in a very short time everything runs perfectly - or seems so. The Bentley book kind of points to this and recommends adjusting the fuel distributor's lower pressure up to 6.5psi from 4.8psi, and then adjust the idle mixture. Doing this before replacing the valve or both at once? Where is the port to read the lower pressure from, and how is the idle mixture adjusted?
Thanks

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89 300E
79 240D
72 Westy
63 Bug sunroof
85 Jeep CJ7
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