im going to clean my throttle body and i was checking the engine and whit the engine running giving it some throttle i saw the center of the upper move to realise that the center bolt was loose to the point a could take off by hand . my car stil has the original 97 stamping upper . is that normal .do you think i was loosing vacuum from there .

None were loose on my factory 96 that I replace two years ago.

Get a torque wrench, and fix them.