Hello. Here’s my situation. My 08 STS (3.6l AWD Base) had some error codes from camshaft and crankshaft sensors and misfire codes. Only Bank 2 sensors were changed, then I drove it while it was misfiring which really messed things up. Long story short, all of the sensors were changed, plugs and coils were changed and so were the ECM, starter, alternator, starter and relay fuses and battery but after all of this it cranks but won’t start and while cranking it’ll give a single hissing pop, not to mention it’s been sitting for about 6 months with either the dead battery that the alternator was draining or with a new battery that was disconnected. Any clues as to what the prob may be? BTW The engine is a swap-in and it’s only got 1 or 2 gallons of gas in it.