My RPM decreases when i don't push the accelerator and my car is either slowing down or idoling and then my battery eventually runs out unless i accelerate. What might be the problem?

 

When your car is slowing down or idling the RPM drops below normal idle speed?

What do you mean by the battery running out?

Does the engine stop running when the car is still moving?

By accelerate do you mean increase engine RPM?

 

yes it does drop below the normal idling stage like it is right above the zero

my rpm decreases slowly until my car turns of and the battery light comes on it always does it on stop lights
when waiting and the only way I can prevent it is if I increase the rpm


my engine turns off when my car is not moving and when slowing down my car sicker like it will turn off and the rpm is below normal

yes I mean increasing the rpm

 

I mean shake not sicker

 

Does the idle speed pick up if you turn the AC on and adjust (not drop in idle RPM) when shifting from Park to R, D, etc.

If the engine otherwise runs OK would suggest looking at the IAC valve. Idle speed is controlled by the idle air intake control valve (IAC). This valve control bypass air around the throttle plate to control idle. The valve can become dirty or fail.

A Google search will turn up many hits on cleaning the valve. Do search on "cleaning IAC valve" plus your engine model. For cars up to 2002 the 4 cylinder was typically a 5SFE, the V6 was typically a 1MZ-FE until around 2004ish.