My wife has a 1999 Nissan Pathfinder that is bucking. The check engine light is NOT on. It's a 3.3 ltr with 4WD. I have changed the air filter, the cap, and wires, the plugs, and cleaned the M.A.F. sensor. This is completely baffling as the check engine light isn't on as I said. Anyone have any suggestions other than take it to a dealership which we live more than 40 miles from, and don't have the money to pay for anyway. The engine has 180,000 miles on it, and the truck has 288,000. miles on it. It has other minor issues unrelated to the way the engine is running but without the light being on, I can't figure out what the issue is.