Haphazard "hesitation" and vibration of entire vehicle

Hi,there…We own a 2002 Kia Sedona mini-van, automatic transmission. For the last few months it seems to start vibrating/“hesitating” all of a sudden. Usually when stopped or slowed down. It usually happens after driving it for at least 45 minutes or so, but usually goes away again. It seems to help to put the car in neutral when the vibration starts at a stoplight, so the engine doesn’t die. The check-engine light is also constantly on (orange), but when the mechanic did the computer check-up nothing showed up. Since this doesn’t happen all the time, the mechanic also has not experienced this vibration. It feels like what happens when you drive a stickshift and have it in gear and mistakenly start taking your foot off the clutch a bit, right before the engine dies…

Light on but can’t pull a code,don’t no where to go with that one. I can tell you that KIA does gives its Techs very good technical assistance,but then you have not tried a KIA tech.

Sounds like a failing torque converter clutch (TCC) this lock up feature is designed to give you better gas milage when you’re cruising at highway speeds but is supposed to disengage when you decelerate. It is just an electric selenoid. If your tranny has one, you can find it and disconnect the wire going to it and in fact, determine whether or not that is the problem. There will be a plug with a wire harness somewhere external to the tranny. You might be able to google it and find the location. If it needs changing, I’d take it to a trusted trans shop, vs a everything else repair shop, Good luck.

Thank you both for your suggestions! We will follow up on both!