What would cause a learn surge? What parts/sensors would I go about replacing?

Hi, this is Bo, an auto expert on RepairPal's Car Genius team! Your Sonata's got a case of the rhythmic surges like it's trying to do the cha-cha while cruising. Since you've already swapped out the PCV valve and noticed some improvement, it sounds like we might be dealing with an airflow issue. First, let's talk sensors. The mass airflow sensor (MAF) or throttle position sensor (TPS) could be acting up, giving your engine some mixed signals. Although, both should fire off a check engine light. A dirty MAF can cause surging, so giving it a good clean might help. The TPS, on the other hand, could be sending inaccurate throttle data, leading to those surges. Another sneaky culprit might be a vacuum leak. Even a small leak can throw off your engine's smooth operation, especially under light loads. The transmission may seem like it's all good, but after consulting our other Car Genius, Devin, he suggested it may be hunting for a gear under load (up-hill) If you need any further advice or if you'd like any help finding a trusted RepairPal shop in your area, please feel free to call us at 877-913-1554.