My 2008 MB GL550 120k is having issue since last week backing from a 1000km towing trip in the mountain. It was towing a 3000lb trailer on highway the engine lost power then died. It could restart but a couple of km it died again and I felt misfire and rough shifting. It was 30km from home so I managed to drive it at 50km/h and restarted couple of times to get home. Check-engine was on with code P0171/0174. I ordered and replaced the MAF sensor and air filters erased code drove it around my community it was fine thought it could be fixed. Somehow the next day on highway it died again with same symptoms -- reduced power, rough down shifting and died. It couldn't start right away but waited a minute it started with rough idle and low rpm, engine hesitating, sometime died without moving. Sometimes it didn't start. I drove it home at low speed. Open the hood check Hoses connecting to air intake they looked fine, no crack no leak whatsoever. While re-install the air intake I found the rubber gasket is broken at one side as shown. could this be the culprit? It's broken at the edge but still seal ok to me. I will order a new one tomorrow to replace it for sure. Meanwhile I'd like to hear suggestions in case miss something else.

The similar issue happened last summer after backing home from a long trip, next day the truck started rough idle throw code 0300/0301/0302/0506. It turned out the intake assembly was not installed properly. I cleaned MAF sensor and reinstalled it had been working fine until last week.