Toyota Repair: Previa 1993 melted wires, spark plug leads, new spark

Question
One of the cylinders wasn't firing.. Suggested new spark plugs cap rotor wires etc..

Did all this to spec and 3 days later it brokedown again. When idled at light or idle dropped it would cut out.

Took to mechanic who checked wires sparks etc and saw that the spark plug leads had melted.

Any suggestions as to where to start? please


Answer
There is only one reason the spaek plug wires will melt and that is because the engine extremely overheated, didn't the mechanic give you any idea as to why this happened?
You need to find out why the engine overheated, if the mechanic doesn't know, take it to someone who can figure out why it overheated to the point that the wires melted and go from there.