I have a 2002 Pontiac Grand Prix GT 2dr with 220k roughly & am noticing between 0-25mph it sounds like its gonna just die, & between 25-65mph it sounds like I'm driving a manual transmission. ???

yes, but it could ne 1 of a lot of things. check your air intake first and make sure nothing is blocking up the airflow. if it is that or something is broke on the air intake system it will only cost around 100 to fix otherwise it could be engine, trans, or many many other problems. if your check engine light is on then tak it somewhere and hook it up. that will be your best bet.