Daewoo I wait 1500cc

Hello, I have a 1994 Daewoo Espero 1.5. When I start it, it runs fine for about 25 minutes, and then it starts jerking as if it's running out of gas (it has gas). When I accelerate, the RPMs are around 1000, then after a few minutes they drop below 500, and if I don't accelerate, the engine stalls. This has happened several times when the vehicle has stopped. I was told it could be the spark plugs, so I've changed the spark plugs, spark plug wires, fuel pump, and fuel filter, but nothing has worked. I need help, please.
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I think your problem is a bit simpler than that. If your issue is the engine speed when it's hot, you should first check the condition of your IAC valve. After cleaning it, see if it improves. If it doesn't, then once the car is at operating temperature, slightly increase the RPMs using the accelerator pedal adjustment screw. The normal idle speed for that vehicle is between 850 and 950 RPM. At operating temperature, it's normal for the RPMs to be between 1500 and 1700 RPM when starting. In fact, Toyota Yaris models start at 2000 RPM and gradually decrease with temperature. Such low idle speeds can cause the engine to stall.