2009 Kia Spetra//car stops at slow speeds but starts right back up

Hello, This may be a bad ground either on the battery or in the wiring harness. Also, a faulty relay can cause this issue, but I have not looked into which relays are integrated into the powertrain control module, so checking them all would be a little tedious for you. If you take this to the dealer or another shop, they are likely not going to be able to replicate the issue, unless there is something you can do that you KNOW will make the engine stall and restart. Otherwise, intermittent problems, especially this one, can be very difficult to track down. That being said, it is better to bring it in for testing before it turns into a start/stall issue.