hi all ex evo owner just signed up. ive been on the mlr for some time but now ive boght a focus rs

had some problems with it today and after a bit of help..on slow gear changes the revs either die down to zero [battery light on] then jump back up....or car just stalls and all lights are on?? if i stop at a junction/lights/roundabout it ticks over perfect?? only on gear changes if any one can help i would be very happy [only got it sunday!] thanks in advance andi