Hello,

   I never heard of a flash that will take care of a whole bank not working. that sounds to me more of a plugged catalytic  than any other thing, a large vacuum  leak from the plenum etc.a computer quad driver can go bad on one cylinder but not on  all 4 cylinders. could also be other mechanical issues more testing will be needed.  to flash a vehicle's  computer although it is relatively simple there are many thing to take into account or damage will occur to the vehicle's computer and even your tool. first you need to register at gm tis-web,  acdelcotds.com for usa  and purchase a 2 day subscription for $55 usd or 995 for the year. but before you do that make sure you have (windows 7 pro 32bit, internet explorer11, java 7)  this could be any laptop but its best on a dual core intel processor. others may work well  but this is what gm wants. does not have to be an expensive Toughbook  the dell 620 and 630 does a decent job and can be bought for 150 to 200 dollars.  when you have all this let me know I will teach you how is done thru team viewer right on the vehicle which is the best way to learn it, forget all those book you read. hands on is the way to go. good luck.