i have a 2010 terrain with no throttle response until i let it run a while. i have replaced the throttle pedal assembly and a new throttle body and did a smoke test for leaks , still does the same

The first thing I would do is obtain a "Tech 2" GM diagnostic tool (or equivalent) and check for any diagnostic trouble codes that remain. I'd also monitor the throttle position information as well as the pedal information. There's got to be a disconnect somewhere along the way that is trying to prevent a safety issue by eliminating throttle response until a certain point.