Service Issues: 06 S60 2.5T Engine aggressive sputter, shaking, stalling.

[Silverlight]

Need big help here. Ive been having issues with this car since i got it (06 S60 2.5T). At idle it always did this slight humming thing. At first it threw Code P0101 for Mass or Volume Air Flow Sensor, Circuit A Performance. I got a new MAF for the second time now and after about 5 minutes of driving it threw the code again. I just dismissed it after this.

Now the real issue:
After driving a few minutes to work i stopped halfway to meet someone, got back into the car, started it up and this happens: Engine starts, rpm drops down as it normally would, whole engine and car starts shaking and sputtering, engine stalls. Start again, same thing happens. I managed to get the car moving by revving up in park as soon as i start the engine. The car runs normally when moving but as soon as youre going slower or come to a stop/ rpm drops the engine starts to sputter again. After this the car threw code P0170 Fuel Trim Bank 1, along with the previous code. We thought it might be the fuel pressure regulator so we got a fuel pressure checking kit. Pressure reads 57 psi and drops normally after engine shuts off. Psi is stable when the engine starts sputtering.
The other possibilities are the fuel pump and fuel filter. The thing about this issue is that it is not always present. After work i started up the car and it had no signs of problems. Got home, checked it by starting it again and the issue is back.

The next morning when i started the engine it wouldnt let me do the trick anymore. Start up, give gas, revs up but as soon as i let go of the gas pedal it just drops down, doesnt let me give gas anymore and stalls. I decided to disconnect the battery for a few minutes, reconnected it and surprise, surprise the issue was completely gone once again. After driving a few miles it started doing it again halfway. Its been getting more constant but still very irregular.

This whole battery thing only made me confused. What could this be? Is the PCM faulty? Maybe the fuel rail pressure sensor? It cant be the MAF and i highly doubt its the O2 sensors. Today i noticed a fairly loud hissing noise at the engine, like a vacuum leak, but that wouldnt make sense to me either.

Mind this car originates from Las Vegas, and now its in San Clemente, CA. The weather conditions might have taken their toll on the parts.

I tried to be really thorough in this post, if anyone has a hint of idea of what the heck this is id really appreciate the help.
Again this whole shaking is not slight. You can feel the engine pretty well, its kind of aggressive. The rpm gauge doesnt move irregularly and im sure this has mostly nothing to do with the ETM.

Also, in park when revving up i heard a misfire in the exhaust but this only happened once.

[oragex]

The replacement MAF is made by Bosch? Most other brands will throw a code.

For the humming, a PCV test - see Youtube

For the misfire, measure the alternator voltage, check cables around it, measure the battery. Remove the serpentine belt and make sure all pulleys on it move easily and smooth.

Inspect the wires to the ignition coils, that run on top of the engine, sometimes these can crack and cause a short if crushed under the small cover.

Don't rush to replace the fuel pump. Unless it has already be replaced with a faulty unit, it lasts the life of the car. Inspect the fuel filter if it's a separate unit.

Then check in this order (google up for details): PEM for corrosion, ECM (or ECU, remove the modules and check for corrosion at the bottom), CEM for water ingress and powering cables

couple of links
https://www.matthewsvolvosite.com/fo...440912#p440912
https://www.matthewsvolvosite.com/fo...hp?f=9&t=80918
https://www.matthewsvolvosite.com/fo...50291&start=10

[Silverlight]

Originally Posted by oragex

The replacement MAF is made by Bosch? Most other brands will throw a code.

For the humming, a PCV test - see Youtube

For the misfire, measure the alternator voltage, check cables around it, measure the battery. Remove the serpentine belt and make sure all pulleys on it move easily and smooth.

Inspect the wires to the ignition coils, that run on top of the engine, sometimes these can crack and cause a short if crushed under the small cover.

Don't rush to replace the fuel pump. Unless it has already be replaced with a faulty unit, it lasts the life of the car. Inspect the fuel filter if it's a separate unit.

Then check in this order (google up for details): PEM for corrosion, ECM (or ECU, remove the modules and check for corrosion at the bottom), CEM for water ingress and powering cables

couple of links
https://www.matthewsvolvosite.com/fo...440912#p440912
https://www.matthewsvolvosite.com/fo...hp?f=9&t=80918
https://www.matthewsvolvosite.com/fo...50291&start=10

Its a Bosch part.
I just did the glove test. It inflated instantly. There is also smoke coming from the oil cap and dip stick. What now?