sp plug and fuel filter change lead to surging idle???

[papiichuulo]

'03 CVPI came into shop with a check engine light on and a slight miss. I didn't even think twice about it since it had 110k miles and replaced the plugs, the fuel filter, and added a can of seafoam to the tank. I checked the codes, recorded them, cleared them and I test drove it for over an hour and it ran good, no sputters, no misfires, and best of all, no check engine light. I called the driver to come and get it, when he did, the check engine light came back on. I checked and found lean codes again for the same as before, bank 1 and bank 2. I found and replaced the source (I think), it was a collapsed pcv elbow on the front side of the throttle body connected to a plastic tube coming from the passenger side valve cover. Now the pcm kicked out a code for "fuel pump driver circuit out of range" and the idle is surging up and down constantly. Any ideas as to why that code would get kicked out after changing the fuel filter?

[Blue)(Fusion]

Maybe the fuel pick up screen is clogged or the fuel pump is on it's way out? Did you check the fuel pressure?

Get a multimeter and check the voltage at the fuel pump, too.