With the onset of cooler weather, my '95 E300D has begun to regularly show a very lumpy idle on startup. If I add the slightest pressure on the throttle, the engine smooths out. Typically, this hunting will go away as the engine warms up. However, on a few occasions, the engine starts with faster idle, around 1,000rpm, which then creeps up as high as 1,500rpm as the engine warms. I can usually eliminate it if I push the accelerator pedal down and let it snap back, like there's an issue with the linkage, though I've cleaned and lubricated the pivot points.

Two part question:
!. Is there a way to manually adjust the idle on the E300D? I don't see anything obvious that would allow me to do that, though I might be looking right at it. My prior experience with engines has been with gasoline-powered ones.
2. Is there some sort of sensor that controls the idle until the engine begins to warm up? If so, where would it be located?

Thanks for your thoughts and suggestions on this.

Regards,
Tom