RPM surge ?

[MercedesTech]

I haven't look into it too much to be honest. Anyways, the trans has begun acting "funny". Never did this before. At certain speeds, holding the throttle steady, the rpms will begin to surge. You can feel the truck pull, and then calm down. Pull, then calm down. Needle is jumping around on the tach, probably a good 300-400 RPM's or more.

Also, the converter wont stay locked. No matter what speed, its only locked while I give it gas. I left off, it unlocks. Its doing this more often then it used to. And at some points, it doesn't know whether to lock or unlock, so its starts jumping back and forth.

This started a couple days ago. It's just acting different, and I am unsure what it is. I am fairly certain, its something to do with OD, Since its only acting up in 4th gear. Any ideas ???

If I were to hook up the proper scan tools, will there be any codes stored for trans ? And yes, I have access to dealership style scan tools.