my water pump failed and have since replaced water pump. Now since repair the truck is losing power, running rough, and have a code for cylinder four misfire. I have already done my head gasket and have magnecore 8mm wires. Anyone have any suggestions. Also getting codes po141, po140, and po1668?????

 

Check for the obvious first. Make sure all wires are seated, pull the plug and another cyl that you can compare it to. Check to see if its wet and such. Have you done coils yet?

 

Also, the P0 codes, from what I can tell by looking them up they indicate O2 sensor issues. I don't know if that is correct, maybe someone more versed in this than me can chime in.

 

P0 codes are generic powertrain codes (meaning that they should mean the same basic thing on any car)

See http://www.obd-codes.com/faq/obd2-codes-explained.php

 

Bank 1 sensor 2 has failed and based on your mileage all 4 should be replaced, which, by the way, had nothing to do with your water pump.