2003 Mazda MPV ignition wire problem
 

Hello, I have a Japanese 2003 Mazda MPV 2.3L 4 cylinder with LW3W L3 engine and it has a problem with ignition wires. So the car starts throttling when you accelerate for the first time, if you don't stop the car rides smooth and I've checked the spark plugs and the 1st and 3rd spark plug had some spark burns on it on the head (the white part). I went to one mechanic and he told we the wires have gone bad so I purchased new wires it worked perfectly for like 2 months but then the same exact problem occured with exact burns (I also changed the spark plugs). Changed them again and few month later again the same problem. And then my friend had some wires and got those for free and changed them again and same exact thing happened. What could be the cause of this? Can it be the ignition coil? Or maybe something else I don't know I'm losing quite a lot of money on these any help would be great. Thanks in advance.