Running problem

Hey people just got my first mk1 golf gti 1.8.  Sorry if I word or spell fings rong not the brightest of people  the problem I have is it's hard to start and when it dus it runs very lumpy (missfires?) and when that clears it ticks over very low ( battery light flashes it's that low ) and when you accelerate it missfires very slightly at first then clears more revs you put on hope this help if not I'll try exsplaning it better if eny problems                                                                
Thanx Si