Bx2200 mower problem

Hi I have a bx2200 I have been having trouble with my engine blow and I rebuilt it I put everything back and it runs fine I put a new fuel pump filter and lines and the engine seems fine till I go to mow it seems to struggle when it's on I tried replacing tranny filter and fluid but I'm not sure if I put to much or to little if that would cause it to mow funny also it vibrates a little when u drive fast in high gear if anyone has any ideas I would every much appreciate it
I hope I explained it well enough if I need to make a video I can