Mercedes Benz CLK430 Engine Not Running

Lately When I Unlock And Try To Start It Just Won't Turn Over But After A While It'll Start Right Up...i'm Thinking A Security Feature Gone...

Car Will Not Start. Replaced Starter And Battery. Just Clicks When Turning Ignition

Rarely My Car Will Have Problems Starting. It Starts And Dies. At One Point, It Completely Wouldn't Stay On And I Had My Fuel Pump Replaced...