Sounds like your Nissan Pathfinder is suffering from a vacuum leak. You'd
need to get this verified by an expert smog check station, not simply an
auto mechanic. The question which needs to be answered is where is the
vacuum leak? A smog repair station can diagnose this problem using a propane
enrichment tool by presenting propane in and around areas on near your
Pathfinder's engine where a vacuum leak might be present. They can then pin
point the location of the leak and perform the required repairs.