Running rough with 2 bars on hybrid battery in slow traffic

Good afternoon everyone!

I have a problem with my 2010 Gen 3 that I need help identifying the cause. I have searched for the answer but have not found it yet.

The other day while on my way home I was stuck in holiday traffic. As usual the battery was being drained slowly and after about 10 minutes of heavy traffic the ICE started when the battery was at 2 bars. While the engine is recharging the hybrid battery if I tried to move forward with traffic the engine seemed like it was about to die and throw up a piston. It would jerk and vibrate like an out of balance clothes washer in spin cycle and make a sound like a the squawk of a large bird. But this would only happen if I accelerated slowly. If I were to accelerate at a normal pace the engine would perform fine. I am worried that I may be damaging something.

I find myself completely confused as to what is happening. The system knows the battery is low and is recharging it so why would it act up when I try to move up slowly? This will only happen when the battery is at 2 bars and the engine is having to charge the battery and power the vehicle. Once the battery gets to three or four bars it operates as normal.

Any advise or links to other threads about this will be most appreciated!

Thanks,
Jeff

 

Cleaned the egr tube and manifold about 10000 miles ago. Cleaned cooler 50,000 miles ago. I’ll do it again or may just replace it this time.

Mileage is 280,000 and climbing.

 

Light dusting only. Manifold was dirty.