2002 Kia Sedona Trans Problem

I have a 02 Sedona with 130,000 miles and a 5 speed auto trans. When cold the trans shifts fine. When hot, trans shudders shifting into 4th, and will constantly shudder in 5th below 50mph. Above 50 all seems good. Changing trans fluid with Kia OEM fluid helps, but it slowly goes back to its old ways. My question is: will the problem causing this leave me stranded, or can I go another 100k with just an aggravation? When looking at fluid charts, it looks like it might be an Underdrive Clutch??? Please advise, Thanks Jasper

How does the transmission fluid look and smell when you change it, burned?

I think that you have big trouble. The shuddering is the clutch or band repeatedly engaging and disengaging. This causes heat build up. Probably sooner rather than later the clutch material will come apart and distribute throughout your transmission.