i had the same problem with mine i used diffrent plugs every time could not find what was wrong so i got some from my locol ford dealer, i just ask for s2 1600 plugs thay gave me motorcraft and i never had any problems after, im running on lucas ht leads and a standard coil. my engine has been taken out to 1700 im running on 17psi with a chip and pace intercooler. as for the battery light well i have the same problem at the mo check all earth wire on the body and clean them, accross the front member u will find a wire that joins just like a male and female conector u will need to have a look at that some times that can be a problem as water gets to it and it run's just under the rad so it my be rubbing and shorting out i have had this problem before. gook luck