98 Buick Century Custom Hard Start under all conditions/rough idle and stalling

Ok so i'm having practically the same exact issue as Sabot explains in this post here.... http://www.automotiveforums.com/t1121531-discuss2000_buick_century_bogs__poor_acceleration. html

I even pulled the same P0170 code.
And what I need to do before I spend a boatload of money and wind up sleeping in my car instead of driving it to work or lack therof is to start a troubleshooting list starting from where Sabot's update left off, i dont even know where the vacuum line is that he mentions and if i sprayed carb cleaner on it would i get a jump in engine RPM or a stall as a test?

What I have done: Cleaned MAF sensor, changed fuel filter
What I have not done: Checked all vacuum lines, Tested fuel pressure, Tested for compression issues due to blown head gasket

there is also a puffing noise coming from the exhaust side of the engine, im gonna grab a bottle of baby powder this afternoon and test for air leaks, i dont believe it is a misfire...

Additional Info: When starting the engine whether hot or cold i need to cycle the key several times to get the engine started, once running after a period of time roughly 30 mins to an hour ill notice what appears to be misfires while stopped, and the more i operate the vehicle the worse it becomes till it will eventually stall out. While this is happen the car will struggle to accelerate however if i can get it up to speeds of above 45 or 50 mph it can maintain it... but after such operation if i turn that car off no matter how many times i cycle that key it does not want to turn back on.

Just like Sabot, a vacuum line had become disconnected and that appears to have fixed the issue. Vacuum line in question was located beneath the coil packs and very difficult to see from either side of the engine compartment. The difficulty of operating the vehicle overtime would theoretically explain the lack of performance as the fuel pump would be straining harder and harder to provide fuel to a depressurized system and lose effectiveness as it heated up. I guess...?
The vacuum line just slid right in and out of the port from which it was originally connected so i must have knocked it loose doing the tune up, a few thousand miles ago...

***UPDATE***
Late but at least its somethen. The problem ended up persisting. I've researched, checked and cleaned alot of sensors and what not before i got into the gas tank and found out the pump was garbage. It appears that the ethanol gas that has sat in the tank for nearly a year before it was driven again ate away at the tank and i was digging out handfuls of rust flakes and sediment.

The pump itself as i was pulling it out of the tank started to get more and more orange the further it got out of the tank and i was shakin my head the entire time. Car is solid for now.