Will not idle. i have replaced plugs distributor cap and rotor. i spray throdile body cleaner into carb and it runs fine until it evaporates

I would give the throttle body a goof clean with carb cleaner making sure the butterfly flap gets a clean due to build up or carbon. If it's not closing properly it will idle rough and possibly cut off. Also might be worth checking the idle control valve.unplug it unbolt it take it off a spray the inside with carb cleaner let it dry and replace. Hope this helps

Have you replaced any of the ignition components? It sounds like it may be time for the spark plugs, plug wires, distributor cap, rotor and ignition coil. These should take care of your misfires. If the idle is still a problem after the ignition tune-up I would look at cleaning the Idle Air Control Valve. This can be done with some carb or throttle body cleaner. This should be done when you have time to let the car sit for while. Drive your car and get it up to operating temp. With the car off, take the hose off between the air filter and throttle body. As you look into the throttle body you should see a hole in the side, this is where you spray the cleaner. Fill this area with the cleaner and let it sit for a while, overnight works well I have found. When you start it again it will run like garbage for a bit, but it should settle out pretty quickly.

If it has spark to the plugs, normal compression, and fuel, it should start. So assuming it does have normal compression, I would want to know if it will try to start by spraying carb cleaner into the throttle body to substitute the injector spray. One of the three components is missing.
Another thing to check is the distributor cap and rotor to make sure spark is reaching all of the plugs at the right time.

don't know what the mats would have to do with this , unless they blocked the travel of the gas pedal,, but anyway ,, check the rotor and the distributor cap for worn or bad spots,, clean them off then try again, your plugs could be worn, and need replacement,, and also , if you have fuel injection,, clean the throttle body, remove the air cleaner tube from the motor, and spray some carb cleaner into the opening, , open the flapper plate and clean that too, wipe off any excess with a clean rag, those are basic steps to check when having the problem your having, if none of this helps ,, then replace the idle control sensor

check the distributor cap,, clean any corrosion that's in the cap,, clean off the rotor tip,, you may need a new set of plugs, and or wires , if these don't fix the issue,, get some carb cleaner and spray it into the carb or throttle body of your motor, and check the idle control sensor in your vehicle

You're probably ready for some engine internal maintenance Timing chain, valves leaking, you know. Almost 300000 miles, Wow

It sounds like you have a vacuum leak or a carburetor problem. Check all hoses and the line going to the brake booster for cracks or leaks. Make sure the carb bolts are tight at the manifold. You can check for leaks using some carb cleaner. Spray around the base of carb while the engine is running, any leak will cause the engine to sputter when the spray hits it. You may want to look into rebuilding the carb or replace it. If its the original its a Quadrajet, they are not the easiest to rebuild but not impossible. If you rebuild it yourself, make sure to get the numbers off the carb so you can get the correct rebuild kit and accelerator pump. Plus you should replace the float when you rebuild since its 30 years old. A thorough cleaning of the carb is crucial before rebuilding. The fuel mixture screws have caps on them so they wont be altered after assembly from the factory. You'll have to remove those caps to remove these screws before cleaning. You can probably find some good info. on doing this at a good parts store. I hope this helps you.

The symptoms sound like you actual distributor is bad. It may have a bad or worn bearing, or possibly a cracked or broken shaft. I would replace the distributor itself.

Spray the intake with carb cleaner to find the vacuum leak. Check where the EGR mounts and the throttle body gasket sense you had both off.

Have you checked your MAF? Sentra's are famous for them having problems, I havent had an issue with mine yet thank god.