Final bump/update for anyone in the future w/ these probs. I ended up caving in and got the IPC fixed. Couldn't find one in any nearby junk shops and no time to wait, got tired of depending on people for rides and being stuck at home. They thankfully waived the labor costs to replace IPC since they were wrong about what was the problem the first time after claiming 'this will definitely fix it'... still, total was $750 for all.
I'll be broke for a long time. All problems mentioned are now fixed though. Car cranks and stays running, no accursed THEFT SYS!
So if you are having all of these problems - try replacing the PCM and IPC yourself. In fact buy them and keep them in your house for the inevitable. lol
Although now I'm having a coolant leak prob... arrggh... but at least that's not a dealer-only fix. Thanks all.
