Hey there, I had very similar issues with my '12 Cayenne Diesel (around 95k km at the time). The symptoms you're describing are exactly what I experienced, especially that black smoke and power loss. Turned out my intake manifold had multiple leaks, and there was a failing EGR valve making things worse. Took it to the Porsche dealer last month, they found cracks in the intake manifold and some damaged seals. The whole intake system needed a thorough cleaning too because of carbon buildup. It was a pretty serious job that took them two days to fix properly. They had to replace the manifold, all gaskets, and the EGR valve. After the repair, the difference was like night and day, smooth idle, proper power delivery, and no more smoke. This isn't something you want to leave unattended because it can lead to bigger engine problems down the line. If you're near any major city, I'd strongly recommend going to an official Porsche service center for this particular issue. They'll have the right diagnostic tools and parts on hand.

Hey, thanks for sharing your experience! That sounds exactly like what I'm dealing with. I'm actually thinking of taking it to the Porsche dealer in my area after reading this. Just wondering, do you remember roughly how much you ended up paying for the whole repair? Also, has everything been running smoothly since then, or have you noticed any other issues pop up? Appreciate the help!

Hey again! Yep, happy to update you! Since getting my Cayenne fixed at the dealer, it's been running absolutely perfectly, like a completely different car! They found and fixed a significant leak in the intake system, and when they hooked it up to the diagnostics, they spotted a Deviation in the intake quantity that's now completely sorted. The total bill came to 425€ for fixing the intake system leak. I know it's not cheap, but honestly, it was worth every penny. The engine runs super smooth now, no more black smoke, and that annoying power loss issue is completely gone. Haven't had a single problem since the repair, and it's been several weeks now. If you're still on the fence about the dealer, I can tell you from my experience it's definitely the way to go. They really know their stuff when it comes to these specific issues. Plus, they'll give you a proper warranty on the work, which is always good for peace of mind. Let me know how you get on with yours!

Thanks for all the details! Just wanted to update you all on what happened. I took your advice and went to the Porsche dealer yesterday. You were right, they found similar issues with my intake system and EGR valve. The whole thing cost me around 480€, a bit more than yours but still worth it. They actually finished it faster than expected, just took a day and a half. The mechanic was super professional and walked me through everything they found and fixed. Took it for a proper drive today and wow, what a difference! No more black smoke, engine's running smooth as butter, and the power's back to normal. That annoying stalling issue is completely gone too. Really glad I didn't put this off any longer. Thanks again for pushing me to go to the dealer. Definitely the right call! Will keep you posted if anything else comes up, but fingers crossed this fixes it for good!