Hey there. I get your worry - something similar happened to my 2016 Hyundai Sonata a while back. The check engine light would come on, and I had noticeable jerking during acceleration plus the idling issue you mentioned. With the jerking and rough feel, there's a good chance it might be a hose problem. The last time I hit the garage I had to change the hoses. The spanking new ones sorted out whichever fluid hadn't been flowing properly. This was causing the choke-ups and the rough feels. Sounded a bit like your car now. Frankly, it was a serious enough issue that warranted immediate attention because leaving it could have been harmful to the engine. Being that your car is a Hyundai with similar issues, I'd suggest you take it for a check-up soon. You may have to replace your hoses as I did. Hope this helps you come to a decision. Best of luck!

Hey, thanks for the quick reply. It's interesting you mentioned the hose issue with your Sonata. I'll definitely look into that once I take my i40 to the mechanic. While we're at it, do you happen to remember what you ended up paying to get your hoses replaced? Also, has there been any reoccurrence or something else since they fixed your car?

Heya! No problem at all, always glad to help a fellow motor-head! As for your queries, the whole hose replacement thingy set me back about 175 quid. And to answer your second question, I'd have to say it's been smooth sailing since I got the hoses fixed, and, no recurrence of those problems. But, apart from the hose replacement, I also had the tank vent valve fixed by the trusty mechanic. Not sure if that's your case too, but after the fix, there's been no problems. No more engine check drama or stalling at idle. It's all pretty much back to normal. All said and done, you should definitely get your i40 looked into ASAP and avoid any major complications. Keep me posted on how it goes, will ya? Cheers!

Thanks a bunch! I appreciate all the insight and options. Your experience gives me quite a clear picture of what to anticipate. Seems like a visit to the mechanic is indeed imminent. And to be ready to part with some cash, haha! I'll make sure I get everything checked, including the hoses and the tank vent valve as you mentioned. Will let you know how things pan out. Here's to hoping my i40 gets back to her usual self soon. Cheers!