The Idle Air Control(IAC) is just in front of the throttle body, an aluminum cylinder with 2 hoses, one going to the top of the vacuum tree. The IAC is probably very dirty. Remove it, spray throttle body cleaner in, shake it real good, repeat several times until it sounds real loose inside.

The Mass Air Flow meter(MAF) is on the edge of the air cleaner box, where the air hose comes out and directs air to the throttle body. It probably needs to be replaced. There are different MAFs for turbo, NA, years, so make sure you get the correct one.
The MAF determines the amount of air that passes through to the throttle body, so that the gas/air mixture is correct. There is a small pin like device that does the sensing, do NOT touch it with anything! There are MAF spray cleaners that sometimes work for a little while.

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