The problems are starting to stack up with my 1994 Nissan Pathfinder. I was trying to figure out why it was cutting off when it is at a idle started by replacing the spark plugs, wires, cap, and button, then I moved on to the fuel filter and was going to change the air filter when I removed the air filter and tried to start it smoke was coming out when the air filter goes is that okay or is it something else that I need to try to figure out what it is!