I changed spark plugs last night. On the way to work this morning, it ran like crap after it warmed up. Crappy MPG too.

Codes are:

P0300 (multiple misfire)
P0131 (O2 Sensor Bank 1 sensor 1
P0137 (circuit condition O2 Sensor bank 1 sensor 2)
P0171 (fuel trim bank one condition)

I pulled the engine forward to get to the rear plugs. Is there something that is commonly disconnected whild doing this. I've check all the vacuum lines around the s/c and all seem okay.

Any Ideas?