FWIW your ECU will start the car as long as the starter will turn the engine,they generally run from low drop-out 5v or 3.3v regulators and these operate down to about 1v above their regulated voltage. A shafted battery will drop to about 7 volts during cranking, any less and the starter won’t even begin to turn the engine. So they’re very capable in brown-out situations.
Also FYI a mildly sticky ICV will be nicely masked by lobbing a nice fresh new battery on the task. Been there, done that too 🙂 When it starts doing it again take a peak at a haynes breakdown diagram of the intake, locate the ICV, remove it (2 or 3 bolts) and clean it with WD40, re-lube with a very light oil and wipe clean, re-fit and all should be well. Free fix in 90% of cases from what I read.