the wheel gap in the front is about 2 in and in the back is 1.5 in, does this mean my back spring, shock or whatever its called worn out, when i go over spreed bumps around 15 mph it hardly bounces up and down

 

maybe your rear struts are gone....do the bounce test...

 

Sounds like struts to me. If they are original then I'd go ahead a replace all 4. As to the wheel gap thing most Maximas i've seen (even lowered ones) seem to have a bit more wheel gap in the front compared to the rear.

 

ya know the front and rear fenders/qtr have different arch. so measurement of suspension height from the wheel well cut out is not accurate measure of the overall suspension height.