nissan pulsar nx

It could be a lot of things. One thing you might check is that the catalytic converters are beginning to get clogged up. When you are driving, there is enough exhaust pressure to get through the clog, but when idling, the pressure is lower and it can't get through the clog, causing the exhaust gases to back up to the engine. It will only get worse and won't run at slower speeds after a while. You have two catalytic converters on that car. One connected to the bottom of the exhaust manifold and one under the car.

thank you I will look into that. I thought it could be one of the sensors, but i am not sure where they are all located. when i slow down my rpms drop all the way to zero. i constantly have to have my foot on the gas.

Don't delay checking it out. If it is a blockage in the exhaust system, you can burn the valves if you let it go on too long. There is a black hose (about 3/4" diameter?) running across the top of the engine from the manifold to the carburetor for the EGR (I don't remember exactly how it was connected, but I seem to remember it ran across the top to the right side of the carburetor). Just take off the end of the hose at the carburetor and start the engine. If it runs a little better with the hose off and dies with the hose put back on (there might also be exhaust coming from the hose end), that's a good sign that the exhaust system is blocked.