So I have a th350 with a 3500 stall and iv never had a problem with it till it cracked the bell housing. So i had the trans shop swap my internals into a good case. Ever scene i Got it back its been acting weird. the first trip i took it out on it didn't want to shift up and now it quit doing that but now i will take off and it will vibrate but if i put it in N and rev it up then back in drive and it will go away. or if i am going down a hill and let it cost then rev into it slow it will be smooth again. I know my drive shaft and u joints are all good. I also have a new flex plate and it still does it. Is it possible there is a air bubble in the converter?
Any help would be great.
Thank you

 

Its fixed... Turned out the bushing in the tail shaft housing slid out so it had all that free play in it and made it vibrate.