Problem solved.. it was an INJECTOR! Lake avoided.
Recap of symptoms: after a light pull the car stumbled and began flashing the check engine light. Power was minimal, and engine was struggling/shaking. Idle was very rough and it started to smell like burning plastic. First code was cylinder 5 misfire, then after 4 miles of driving the codes expanded to cylinder 4 5 6 misfires (see first post). Checked park plug in cylinder 5 and it was completely soaked with fuel.