Moin an alle It’s about a C70 Bj 2003 200PS automatic I just wanted to change the spark plugs. I also did. Now it feels like a cylinder is missing. Engine control light went on and then it even started to flash. Speed fluctuates something. All ignition cables and plugs controlled. No improvement. Then the old spark plugs reinstalled. Mistakes felt worse. Now it has also gone unround in idle run. Did I break something? Just changed the spark plugs. I am grateful for every hint. Greetings Thomas