2009 Outback Stumbles at idle & misfire codes

[iriejedi]

I recently purchased a 2009 Outback 2.5L with a bad engine knock for a low price. I ended up installing a used 2.5 longblock from a 2008 Legacy. Now that it is together and running I am having troubles with a "stumbeling at idle" issue and running rough at low speeds on my 09. However when I reset the computer the 4 codes I continually get are a missfire on each of the four cylinders. Have you guys seen this before? BTW I purchased the car as a fixer and just put a used 100,000 mile longblock (longblock only) in the car since the old one was a knocker. Did I miss something? Should I have changed out the cam and crank gears? I do not have history on the car prior to purchase and I don't really remember a stumbling when moving it in the driveway prior to engine swap. The misfire codes seem to appear after a little bit of idle or stop and go driving. Runs great at hwy speeds and does not stumble or stall while driving on interstate. Just at stop signs and such.

Edited August 8, 2017 by iriejedi