HI.Just wodering if anyone else has a distinct hissing noise like air being restricted that is most noticable at idle. I took my '99 Explorer to the dealer and the mechanic said it is normal and is common with all 4.0 SOHC engines.....although he remarked that he can't believe there hasn't been a recall over this...Thanks

 

The airflow pattern through the filter and the air mass sensor is the culprit. Typical 4.0 Explorer.

 

Thanks for your input..much appreciated!