Volvo C30 Jerking Acceleration

Jerking, reduced power, check engine light… Definitely sounds like a sensor issue, possibly related to air intake. Has the engine stalled out at all? Does the engine run rough, especially at idle? Have you checked for any obvious leaks around the intake manifold or any disconnected hoses? More information is needed to give a better assessment.

Yes, the engine does stall at idle sometimes, and the running is definitely rough. Could a faulty manifold sensor cause all these problems?

The symptoms you're describing, especially the stalling and rough running combined with the exhaust smell, strongly suggest a leaking intake manifold. Scorching can cause leaks, leading to all sorts of issues. It's highly plausible a faulty manifold is to blame, or at least a sensor on it. It’s best to get it properly diagnosed at a workshop; they can pressure test the system and pinpoint the exact source of the leak.

Thanks for the insight. Took it to the shop, and you were right. The intake manifold was defective and leaking. Repair cost me 1180€.