i also overheard the mechanic saying it has certain nnumbered or types of plugs to work on certain engines, my bro had just got normal ones for his 1.6 4AG and they burnt off in 2 weeks

Put the right ones, and everything stopped giving trouble for his....
mines is the plugs, also check the wires etc to see if its going bad, as well as the wire harness, cuz i seen this guy with a bad connector by the engine bay and when he starts it just clicks, when he moves that connector a bit to move the wire, it like touches the other and starts, but if your driving, the vibration causes it to go out and on and out and on and makes the car seems as its missing, it'll just bup for a second like its complety off and back on 3-4 times and then go normal with the higher rpms being smoother an dno vibration.