exhaust backfire on 911 Carrera 3.2
 

I posted this in another section which may have been the wrong area so here it is again:
I am new to the forum but not to 911 ownership. Currently I havea 1987 Carrera 3.2 and have been experiencing prolonged and inconsistent popping/backfiring from the exhaust. From cold it will pop a few times and when warmed up will run for about 15 minutesbefore thepopping startsagain but inconsistently, mostly low rpm or between shifts. It is also missing at the lower rpm's when it warms up in any gear, when it hits about 3500 rpm it kicks in strong but will actually "jerk" on accelleration if pushed harder under that 3000 mark. Any one have any ideas what may be causing this?
One other thing that may be related is the headlights flicker a bit at idle and the oil pressure guage will flucuate as well. I am beginning to suspect itmay be anelectrical related problem.