just to clean the strainer looks to be a really easy job:
REMOVAL (LOWER)
WARNING:
To avoid the danger of being scalded, do not drain engine oil when engine is hot.
1. Drain engine oil. Refer to LU-9, "Changing Engine Oil" .
2. Remove oil pan (lower) as follows:
a. Loosen bolts with power tool in reverse order as shown to
remove.
1. Oil pan (upper) 2. Oil pressure switch 3. O-ring
4. Relief valve 5. O-ring 6. Oil cooler
7. Connector bolt 8. Oil filter 9. Drain plug
10. Drain plug washer 11. Oil pan (lower) 12. Rear cover plate
13. Oil strainer 14 O-ring 15. Oil level gauge guide
16. Oil level gauge
PBIC2883E
PBIC2890E
Revision: September 2006 EM-28
OIL PAN AND OIL STRAINER
2007 Xterra
b. Remove oil pan (lower) using Tool.
CAUTION:
Be careful not to damage the mating surfaces.
Do not insert screwdriver, this will damage the mating
surfaces.
NOTE:
Slide seal cutter (1) by tapping on the side (2) of the tool with
hammer.
INSPECTION AFTER REMOVAL
Clean oil strainer if any object attached.
INSTALLATION (LOWER)
1. Install oil pan (lower) as follows:
a. Use scraper to remove old liquid gasket from mating surfaces.
Also remove old liquid gasket from mating surface of oil pan
(upper).
Remove old liquid gasket from the bolt holes and thread.
CAUTION:
Do not scratch or damage the mating surfaces when cleaning
off old liquid gasket.
b. Apply a continuous bead of liquid gasket using Tool to the oil
pan (lower) as shown.
Use Genuine RTV Silicone Sealant or equivalent. Refer to
GI-47, "Recommended Chemical Products and Sealants" .
CAUTION:
Attaching should be done within 5 minutes after coating.
c. Install oil pan (lower).
Tighten bolts in numerical order as shown.
2. Install oil pan drain plug. Refer to EM-27, "Removal and Installation" .
3. Installation is in the reverse order of removal.
NOTE:
At least 30 minutes after oil pan is installed, pour engine oil.
To replace the pump, you have to remove all sorts of things as you need to remove the upper pan as well per the fsm..... You got to remove the timing chain cover, primary chain, front drive axles etc etc. it's ugly.
I would try cleaning the strainer and you just drop the lower pan, which is easy to get to, clean the strainer and put back on. Hope that fixes it or else it's a big job- unless the fsm is wrong.