My 2003 hyundai sonato drives up on its own and tthendown shifts and they starts choking slamming noise from transmission no codes

Hello, Dave here, contributing to RepairPal and providing expert advice since 2010. Shifting issues without trouble codes is almost entirely always caused by internal mechanical issues. Hands on inspection will be needed. I expect a poor outcome with a very likely internal issue that would require replacement of the transmission assembly. https://repairpal.com/auto-repair-near-me Click the link or call us at 877-913-1554. We'll gladly find you a certified RepairPal shop in your area.