Q: Idle Problem/Engine Misfire Code P0300 P0301 P0303

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I have a 01 chevy cavalier z24 and i am having problems with the car idling it will idle harsh and die i hooked up my probe and it came back with 4 codes all pretty much saying misfire on cylinder 1 so i changed the Plugs/Boots then tried again same problem same code so then i changed the Ignition Coils and the Ignition coil module same problem. Then i took off the vacume hose to the fuel pressure regulator and seen it was spitting some fuel so i thought that might be the problem i changed that today and still same problem. If i am going down the road 2k+ RPM it seems to run fine however if i stop the car will cut out and die. I was wondering what this could be i have spent $400+ on it so far and i really don't want to dump any more money into it until i'm sure what the problem is. Any help would be appreciated thanks.

I have Replaced: TPS Fuel Pressure Regualtor Plugs/Boots Ignition Coils/Module Ignition Housing

My car has 124000 miles.
My car has an automatic transmission.

Hi there. Check the spark plugs and fuel injectors for cylinder 1 and cylinder 3. Both cylinders are misfiring. If the plugs are good and the fuel injectors are firing, then there could be a problem with the internals of the cylinders. There could be a burned valve or the rings on the pistons could be stuck shut. Put a compression test on all of the cylinders and check the compression. If cylinders 1 and 3 are lower than cylinders 2 and 4, then there is a leak in the cylinders. Then you would need to put in a leak down tester (requires compressed air) and check to see exactly where the leak is coming from. If you need further assistance with your engine misfiring, then seek out a professional, such as one from Your Mechanic, to help you.

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