I got two problems that may or may not be related. If the car sits for more than 10 minutes than it has a hard time starting. I can turn it off and on and it starts right up. Next probelm is rough idle when in gear. If i shift to neutral it runs smooth. Runs normal when accelerated and my mpg are normal. Recently replaced plugs and wires and fuel pressure regulator.

 

The hard starting is probably the check valve in the fuel pump is bad. It takes a while to build up pressure when the fuel in the line drains back into the tank when the pump is not running. The rough idle may also be caused by a slightly weak fuel pump.