Hello, I am new to this forum and need some help. We have a 1999 Nissan Quest and recently our fuel milage has gone way down. I have replaced the spark plugs and the air filter, does anyone have any other suggestions that may help?

O2 sensor.

Our 99 Quest recently was exibiting poor gas milage as is yours. Then about a week ago there was very poor acceleration to go along with it. After a week at the dealer (Who did a lot of head scratching) the problem was traced to a rust clogged exhaust pipe forward of the catalytic converter. If you start to experience poor exceleration you may have the same problem. Dealer said that the pipe has a sleeve and when it started to rust it slowly constricted the exhaust flow which affected gas milaege and slowly was choking the engine till it robbed power. ($1,100.00 repair, ouch) I hope yours is a simpler problem. Good luck and let us know what you find.

Mark

$1,100!!!! I hate dealerships. Please tell me your van was still under warrenty. Please.

I wish it was, I had to bite the bullet on this one. I originally had the van at an auto repair shop that a neighbor works at and they could not trace the problem. I had no choice really but to go to the dealer. The van has 120,000 miles on it and is 5 years old. This is the only expensive repair we have incured in that time so I am not to broke up over it. The dealer had the van for two weeks and only charged us $87.00 for a rental car for the duration. It now runs great, it still looks great and a new car or van (This one is paid for) would cost thousands more.