My 1999 civic lx exaust manifold has been replaced plus the catlyst converter and both o2 sensors,still my car runs at idle and when put in gear car shuts off.The fuel pumps comes on and the filter is good.What are some common problem with the fuel system.That im missing thats usual with the Honda?

 

Scan for ECU codes. Check fuel flow from the return hose. Check the cam timing.