Has developed a slow idle problem

Hello,

It sounds like you might have a dirty idle air control valve (IAC).
Over time the IAC can get dirty due to having larger air particles buildup inside the valve. This will restrict air flow and can impact the idle quality.
The IAC is located on the top of the intake manifold. You will have to remove the engine cover to access it (see diagram).

The IAC can be serviced by cleaning it out. This will allow the proper volume of air through the valve.

Here are some helpful articles:

https://www.2carpros.com/articles/how-a-idle-air-control-valve-works
https://www.2carpros.com/articles/idle-air-control-valve-service

I have attached diagrams for your reference.

Please let me know if you have any questions.
Thank you.