lean can also be caused by bad intake manifold gasket or exhaust manifold gasket, or other leak in exhaust before the O2 sensor... the leak would be on the drivers side of motor..... did the #5 coil fix the code problem ? If not, possibly a plugged injector could be the problem...if you had fuel trim values you could see any possible fuel related problems.

 

 

just an idea. LEAN means excess air or lack of FUEL.. My though was that a bad injector (plugged) could cause lack of fuel, and could cause the misfire on #5... they are both on the #2 bank ....... I don't know if this is possible, but if you had a code reader that would give a snapshot of computer values, you might look at the FUEL TRIM and see if it is trying to compensate for a plugged injector or similar .......... If you don't find a VACUUM leak, this might be a place to look next.

 

also , check the electrical plug onto the COIL and the INJECTOR in the area you were working. Make sure the wire didn't pull slightly out of the socket, and that the socket is seated good into the COIL and INJECTOR.