Hello all. I apologize about this being about my 3rd or 4th thread on this issue, but it seems that every time we believe we fixed it, the problem comes back. Anyways, ever since we bought the car, we've had a P0101 code (MAF sensor). The issue would be that when coming to a stop, the car would drop RPMs to a near stall. Then it got worse- the car would actually stall. Then it got even more worse, and while driving at highway speeds, the RPMs would drop to around 800 while cruising. The car does hesitate when accelerating and sometimes stutters a bit. We replaced the MAF sensor, MAP sensor, FPS sensor, spark plugs, cleaned the throttle body, replaced the O2 (oxygen) sensor, and also replaced the coolant temperature sensor and thermostat (coolant problem). Anyways, we've had it into a Volvo certified service shop (not dealer) and they tested for vacuum leaks.They found one and sealed it with tape. They also replaced another hose they suspected could be leaking. We ourselves (my dad and I) also replaced the PCV hose when changing the sparkplugs. At one point a P0172 (too rich) code came up, but it cleared after replacing the coolant temp sensor and thermostat. The stalling issue did seem to go away for a while (with the RPMs still dropping when coming to a stop) but alas, the check engine light remained on with the P0101 code.
Today I was out driving and the car stalled when turning the corner to pull onto my street. Started right back up fine. Then later I was driving and accelerated from a stop light. Then the car in front hit his brakes to a complete stop almost immediately after, as did I, and the car stalled. It again, restarted just fine, but I was almost rear-ended because I had to start the car again.
I will link a video below to what I believe is a vacuum leak, but I would like the opinion of everyone on here. You can hear very loudely a hissing/whining noise over the sound of the engine. The noise SEEMS to be coming from the hose that has the little red inlet on it as well as the top on it (the tape the volvo repair shop put on). But I can't tell if it is coming from this hose or the whole brake booster system behind the engine. Is this the sound of a vacuum leak or something else? We tried carb cleaner spraying and could never get the sound of the engine to change.
Any and ALL help would be greatly appreciated, as we just want this fixed!!
Also worth noting the car is NOT a turbo model, it is 2.4i Car has 118061 miles on it.