Odd throttle issue

[Suzaku]

2008 Yaris MT sedan got used from Carmax. (mostly stock -more later )
only 55k on it

Had an odd scare on the way home from work last Thur.
while stopped at a lite about 1/4 mile from my home, while waiting... I noticed the dreaded "check engine" light had come on...
traffic light turns green, ease up on clutch. step on gas... STALL...
PANIC mode!
Restart motor... ( it does ) clutch in, at idle.. step on gas... NOTHING HAPPENS.
try again.. NOTHING...

Pedal to the floor and there was only a slight raise in RPM.
tried to restart 2 times. no change.
got it pushed off onto a parking lot.
trying to work out what could be going wrong.. thought it might be a fuel problem... shut it off.. turned on the ignition w/o trying to start & left it on for 30 sec
shut it off. did this 2 times.
tried to start again... MAGIC!! all working again normal...
Took it to my local shop. he pulled the codes ( did not say the exact codes)
Said the error had something to do with the gas pedal / throttle body system but could not find any reason as it seemed to be working OK.
to come back it it did it again.

so far... its been ok
Cleaned the throttle body today.. there WAS some back stuff in it.. but not that much :/

and now for the sort of non-stock bit...
I have a high power audio system in this car
RF PUNCH 800 & 100 the 800 is a high draw on the bat as much as 60 amps (peak) and the other amp can draw up to 10 amps.
needless to say, when I have it turned up very loud. the lights in the car dim.

The day this happened, I had it up quite loud.
I also had the defroster blowing meaning that the AC was running.
I do not know.. if this had any part in it at all.. :/
as this happened when i was idling at a stop light.

I am now adding a 3 farad cap to the system to heal with the load.
I have had this setup in this car for 6 months and this is the first odd thing to happen.
and I have had this setup for 10 years in other cars.. so this happening is a bit of a mystery.

any input would be helpful

tks