My wife drives an '02 Jeep Liberty 3.7L V6. The original engine crapped out a month ago with 132k miles on it. i dropped in a 3.7 with 29k miles on it from an '03 model. It has worked perfectly until now. I'm getting codes P0351, P0353 and P0355. I dropped new plugs in when I dropped the engine in so I tried switching the coils around and still got the same results. Unplugging the plug one by one on that side made no difference in the way the vehicle ran so obviously no spark. If i unplug say #2 then it makes the vehicle run even worse. That whole bank on the driver side is the problem. Could this be because of the pcm going bad? I'm running out of ideas so any help is appreciated.

 

try pulling out the fuel injectors and clean them. Use some Vaseline on the O-rings to lube them and so they dont tear when you put them back in.