Ok so I'm pulling generic code p0700. Which is just an indicator... But I can't read the tranny one, yet, will try to find the tool. But I was wondering if anyone had any ideas. What it does is when first started everythnig is fine (even with CEL on) I can use my change my "touchshift" gears and it shift fine untill it shifts to about 3rd or 4th then it stays in that gear even after deaccelerating. After a restart it is fine untill the process goes again. I had the whole rear end subframe and differential and most suspension components replaced. My mechanic got the parts and should be the correct parts out of the exact same car. (Still can't rule out that it's a different differential). Anyone know what I could try?

I don't think anyone can help you, if you do not indicate what car , model, year and other details.

Good point, sorry about that. 2000 C230K Sport. Also I did search and found that changing the Tranny fluid seems to help on some ML's and whatnot and will probably try that, but wanted some more feedback. So yes I did search.