Peugeot 206 GTi stalling on pull off?

My 206 GTi is stalling when I pull away and it seems like the lights go dim.. Sometimes it loses voltage completely when I pull off... Also got a problem with my stereo where it cant distribute enough electricity to run all four door speakers at the same time(I have to set the stereo to only play through one corner or it wont go to high volume)... When I start the car and its idling high the car seems alright but it'll eventually idle at 720 but it'll be juttery like its coughing... Main problem is the stalling cause I have to get it up to sometimes 3000 revs then bite the clutch as the revs go back down to get it moving and even then its basically kinetic force that getting it rolling... My diagnostic computer said there is a "b" circuit short out in the wiring and low voltage to the coilpack?? Anything I should check??