99 Taurus Code P0175

hi everyone... my sister has a 99 Taurus SE with a 3 liter v6, the other day, it stalled and would not restart for her... i ran it for codes and it came up with P0175 saying that bank 2 was running rich... i was unable to find much in the way of direction of where to look for the cause of the problem, we cleaned the pcv valve but it seemed like it wasnt seating properly.... we got it running, cleared out all the codes, she drove it for two days and now is describing a misfire to me.... im totally clueless on this one... any and all ideas would be appreciated thanks :)

So now with the misfire does it still have the same code?

-Rod

yes, it still gives the P0175 code... along with the misfire on cylinder #5 code... we pulled the plug on that cylinder and it looked pretty bad so we replaced all six plugs... didnt fix it... we then switched injectors around but the misfire didnt follow the injector... we changed out the coil pack with the one in my girlfriends car (they have the exact same car) and it seemed to not misfire... we took it for a ride, got back it began running rough again and it was running very hot...

Did you also try swapping the plug wire for cylinder #5? How about putting the parts from your sister's car (coil, plug wire) on your girlfriend's car and see if they impact how the gf's car runs.

From the factory service manual, the possible causes for a P0175 are:

Fuel system

-- Excessive fuel pressure.

-- Leaking fuel injector(s).

-- High fuel pressure.

Ignition system

-- Spark plugs.

-- Spark plug wires.

-- Coils.

Induction system

-- Restricted air inlet.

Base engine

-- Oil overfill.

-- Cam timing.

-- Cylinder compression.

-Rod

ok so after another day of toil... we have decided its a head gasket or head gasket related... we pulled the plug on cylinder 5 to check the compression and there was coolant on the plug ... since that is beyond my ability and since i've already spent 3 days with it, we took it to a garage... thank you for your help :)