Master warning light, check engine, car symbol with exclamation point

I had my '04 (133,000 miles) Prius out for state inspection. I left and made a few stops, including filling up gas tank. After a total of about two miles the car abruptly shut off at a traffic light and the master warning light, check engine light, and some other lights came on on the dash and the car with the exclamation point on the info screen. The traffic light was right by the garage where I had it for the inspection. I went back there to take a look.

The took it in and got a 3191 code which apparently indicates a failed start. But it was starting, even though I believe it was shutting off more than normal. After reading codes he took it for a ride and got stranded just down the road. When I got to the car it wouldn't start. I think the master warning light and other lights were still coming on, but after I tried several times I noticed that the master warning light and the car with the exclamation point weren't coming on anymore. It was just as if I was putting it into accessory mode where the dash lights come on.

After letting it sit for a while (maybe 15 minutes or so) and in the meantime disconnecting and reconnecting the negative wire on the 12V battery in case something had to be cleared from the system, it started for me again. But it would hardly move and shut back off. I switched the display to show the hybrid battery charge and saw that there was only one bar. It was enough to start the car if I let it set for a while, and it showed an arrow indicating some charging, but the engine wouldn't go hardly above an idle with the peddle depressed, and it would soon shut off. I don't know at what point the hybrid battery became drained, but it seems that once it has the engine running it should take charge. The battery has been staying in the normal range of two bars from full as a norm.

A thread I found here mentioned that maybe cleaning the throttle plate might help. I suppose that if the engine wasn't running right the mechanic may have drained the battery running it on battery power, if the car would have been willing. Any ideas?

 

Update: The car was the same way this morning. I cleaned the throttle plate. In doing so I unplugged the wire going to the air cleaner housing. The car would keep running, but only at an idle. I plugged the wire back onto the air cleaner housing and the car shut off, acting like before. I left the wire off and it gradually would take more throttle and charged the high voltage battery to half charge. At that point it didn't indicate any more charging even if I kept it running with a depressed pedal. I ran the car home with the wire disconnected and it finished charging and acting normal (except that when I first took off there was a shudder when I accelerated, which I don't understand). When I got home I connected the wire again and the car seems to be back to normal except that the check engine light is still on. All the other lights are off as normal.

So the only two things I did different was to clean the throttle plate and disconnect that wire. I'm not sure which of these things made it start charging and continue running. Even when it started to continue running, it seemed to be a gradual improvement as the battery gained charge.

 

Thanks, I will do that.