I have had my '87 Vanagon to a trusted mechanic for several tries to fix a problem with a very high idle when cold, along with intermittent rugh running/stumbling when cold. 

Both he and I have tried various combinations of other AFMs and idle control modules, and he thought he finally had it fixed with a different idle control module and throttle body. It is somewhat better,but my idle still goes up to 2600 RPM within 30 seconds  of startup, and there is quite a roughness, like it may not make it down the road, for the first few minutes. When the engine warms up, the idle and running are fine. The temp II sensor was already replaced. I tried unplugging the oxygen sensor, and don't see any difference. 

Any ideas?
Thanks,
Ed in CT