Prius not idling when Li battery is low.

I have attempted to look through the forums for a problem that I am having with my 2004 Prius but I had no luck. I got stuck in traffic for over an hour yesterday and my Prius' engine would not idle and charge the Li battery. There were two bars of charge showing on the display, and the engine would start, but would quickly stumble and die. It would continually attempt to start, but stumbled each time and died. The engine ran fine, and the Li battery recharged once I was out of traffic. It also starts fine when it is cold. Is there possibly a control module failing when it gets hot? Could a weak 12 volt battery cause this? Need advice. I work on my own Prius. Does Prius Chat have schematics for this version of Prius available?

Thanks for your assistance!

 

Hey thanks for the corrections! Spark plugs have been changed out at factory suggested intervals. All batteries are original and pushing 251,753 highway miles on them. I will check the air filter and I can check the throttle body. That should be a piece of cake. I found a thread about using the MFD to view battery status. Going to try that as well. Thanks for your response!

 

Hey thanks everyone! Batteries appear to be ok and charging system appears to be ok via onboard diagnostics. Looked down throttle body and it is gummed up. I hear a crusty sound when I move the butterfly via twisting it. Sounds like the motor gears need cleaned on the throttle body. Will be cleaning throttle body this Saturday with my chief automotive technician (12 year old son). I am also going to check the inverter? coolant pump behind the driver's side headlight for correct operation. I will keep searching the forums and checking here for more information. Trying to hit 300,000 miles. Again, thank you all very much for your input!

 

I estimate that I will reach 300,000 miles on it in approximately 12 months.