Buddies, here is my sparking story

Few days back, my plug wire snapped as one of it got into radiator fan, hence my car start jerking. To resolve the problem I installed a desi plug wire to which my mechanic protested as he have a lot of negative comments for it.

Despite that my car ran superbly with it and gave me a lot better mileage. Even better than before) But the only catch was that my FM had a lot of statics.

My friend got me a original Japanese wire (used), hence i thought i shall replace it. Today I replaced it but to my surprise it starting to jerk again. I replace it back with the desi one but the jerks we still there but not as much. Now i went to my mechanic, he checked the plugs, readjusted the tappets and cng setting yet the jerks were still there. Long story short, i bought another desi plug wire but the jerks are still there but not as much as it was with the Japanese one. Now my mechanic suggests that i MUST install new wires.

I leaves me with following question that
1) if I leave the car the way it is, would it affect the engine?
2) how come all the wires which were ok in the morning still being faulty all of sudden.
3) Would it impact my car mileage ?
4)if i go for the wires, which one should I go for??? Bosh or ?????

Ur suggestion will be highly appreciated!