I have a 1997 Discovery that stalls at idling speed after the engine warms up. Before this problem began, the oil light would flicker and the RPM would drop to approximately 500 RPM after the engine warmed up. Now it stalls when idling or slowing down. After stalling, I have to press the gas pedal while cranking the engine to get it started. When the engine is cold however, there is no problem getting it started.

I have scanned the computer and received the following codes:
P1313
P1314
P1316

All the preceding codes are misfire codes and are probably due to old spark plugs. I am thinking the fuel pump is faulty but would like some advice first before going any further.