Look on the driver side /inner fender ..little 1" square sensor with a white/plastic vac hose going back to the intake..that reports intake p/vac back to the Control unit..
Check that plastic line....they crack from heat fatique...I just junk them for a full length rubber vac line. Check the elbow at the intake end of that line too..they split.

If you have the CD or schematic , it is sensor B5/2...

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A Dalton