i just got an 01 grand cherokee i6. and when it is ideling, you can hear it idle up and down and up and down,.
does anyone know what this is?
there is 106000 miles

thank you
jim

u left the a/c or defrost mode on?

nope. none of that is on.

any trouble codes stored in the ecu/ecm?

I am new to jeeps, but there is no engine lights on.
Also it only idles up and down when it gets warmed up.

Check for vacuum leaks. Also, cleaning the intake/throttle body might help. Post back after checking those.