Hi Ive never posted on here before but I find these forums extremely useful for info on all things Ford as you lot seem to know so much! (I was taught flattery will get you everywhere! )

I have owned my Focus for 2 months and since Ive owned it, the water pump has leaked resulting in a fix under warrenty and an apparent oxygen sensor failure which is to be fixed soon (which may be linked to my problem) I know my post is ridiculously long winded but I would very much appreciate you lend me your time and help me diagnose whats wrong with the RS.

Got back from a long day of travelling a few hours ago and the Focus seems to be either playing up a bit or what I dont know! I know very little mechanically so was wondering if someone could help me out!
Drove from Poole on the south coast back up home today and everything seemed fine until we got to Northampton. The battery light came on just as we got on the M1 which Ive been told suggests the alternator is broken. In the end my lights were as dim as side lights but the car was running fine and managed to get to my turn off. Then the battery light turned off and my lights got full power again. It kept on flickering on and off all the way back home with the lights dimming and powering up everytime it went on and off. It finally started seriously going mad between three roundabouts about 3 miles distance between all three. First stretch the ABS light came on, battery light turned off, went off, battery on etc but total loss of all lights in near pitch black. Got across 2 roundabout on the final stretch home and then it seriously playing up, still no lights, started chugging and jerking back and forward till the next roundabout (another mile), ABS light on, airbag light on, battery light on, but the engine management light never ever came on the whole time. Managed to chug our way to the roundabout at literally 30mph with hazards (which barely worked) on crawling down the side of the road. Finally cut out (After 3 miles?!) on the roundabout! Managed to roll into a sideroad where the car wouldnt start at all. Left it 5mins and it started?! Somehow got it home but it sounds completely shagged! Really tinny and its backfiring a bit. Then I started it up about 30mins ago and everything is fine with lights working properly and everything?!

Any suggestions as to whats wrong with it?