What could cause my car to die at a stop?

My car is an 04 Ford Explorer 4.6L Eddie Bauer. Alternator a rebuild that I put in 5 months ago, battery is still good but will probably need replaced by the end of the year. It starts up, but I need to put my foot on the gas or else it just struggles to start. When the car is running, it'll only stay running when I keep my foot on the gas, or else it just dies (but starts up again fine) RPM's in park/idle are around 500-700 RPM. If the car doesn't die at a stop, the RPM's are around 300-500 RPM. I've heard on these Explorers that it could be the Idle Air Control valve or Mass Air Flow sensors getting really dirty that can cause it, but I'm open to other possibilities as well.

Thanks for any help!

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