I can't figure out this F*-%!n misfire out!!! (W208)

[jtoma878]

My CEL light is on, and it has been throwing code P0305 for a couple months now. I have replaced the plugs on that cylinder, changed wires, swapped the coils around, and just recently re-installed my injectors after I had them cleaned and flow tested, same result (even after clearing the codes)

Symptoms of the misfire are: rough idle, and off-key shifting: sometimes she almost redlines off the line before shifting into 3rd (when i am hard on the accelerator off the line).

Any idea on where I look next???? I'm about to break down and bring her to the stealership :-\

Thanks in advance