losing power and worse gas milage
 

seems like ever since i had my trans checked out because of a very hard bang. not the kind you can hear but can feel it when i'm at around 15 to 20 mph and i accelerate normally it feels like the trans or drive shaft has some play or loose, he tried a fluid change with no improvement but now the h2 isn't shifting the same, when i take a turn up a hill seems like it doesn't down shift at the right time and feels sluggish until i stomp on it and force a down shift. any thoughts??? 2008 h2 sut 112k miles

Could be a plugged catalytic converter. That is the symptoms of a plugged cat. You need to have an exhaust back pressure test done.

Would i also feel a bang or thud when i accelerate from a coast?

Possible I guess. That could also be a sign of a failing transmission.