700r4 stutter

HI I have a 89 gm serra with a 700r4 recently blew up the sun shell and sun gear. So I took it apart and I rebuit it. I followed a shop manual and after I got it back in I started driving it a few days latter I got down on it and it runs like a top. Untill I noticed it stuttering or shuddering at very light throttle it does not matter what gear I'm in or how fast as long as my foots of the gas and I then press it it happends. It still does it when my I hold the break and at higher rpms sometimes too so I don't think it's lock up. I also watch my rpm gauge and when it shudders the rpms stay the same so I don't think it's engine? I'm stuck on this one it's been 2 weeks since it started. Any advice is appreciated.

Believe it or not, there is a product call Shudder Stop available at NAPA. I think there may be other products that do the same thing, but I used it, and it worked almost instantly. A friend of mine suggested it after his friend used it on a 91 OCC with the same issue.