My 1998 E320 has erratic idle when setting over night. After it warms or I drive for a few blocks runs fine, idle is smooth.
I have read that the IAT can cause this or fuel pressure issues.
Does this car have IAT? How do I test ?

Could also be fuel pressure bleed-off.
Fuel pressure is retained by the fuel pump & filter.

The IAT is part of the Mass air flow sensor & would generate a check engine light if defective.

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