1996 BMW 328 fault finding

Please could you help we have had the bmw now for 3 months the first thing that went wrong was a tale light kept blowin and while accedently looking at the fitting for the hard top roof noticed that a electrical connection that the hard top fits into has broken so we made safe and the bulb was fine although sometimes the rear light failier comes up on the on board computer but the light is ok making me think that the broken connection must still be shorting somewhere, then after some weeks the car started to cut out at low revs mostly when you changed gear to a lower one then we took a long drive to reading from margate and as we got to our destination the car started to rev really high as you were changing gears we just had to keep stoping and waiting for a while and doin the trip in short journeys it got us back but is running realy slugish and is still cutting out on us could someone please help us as we love this car and cant afford to loose it or be ripped off by local garages in my area thanks to anyone who cane help us