This must be a H O T running engine. I took apart my harness last weekend for a problem of hesitation under heavy acceleration and finally at idle. 92.000miles.

The heat of the engine seems to "bake" the insulation on the harness, and the vacumn tubing, for that matter. When a mechanic replaces the spark plugs, it's easier to "flip" the harness out of the way with the resistors in place. Therby putting rotational forces on the wires & insulation.

Each time this happens, the now baked non flexible insulation cracks and exposes the underlying wires. Eventually, arcing and finally grouding out the firing of the sparkplugs.

I was able to buy the new plugs with wires attached and solder them into the harness, connecting to the "good" wire (flexible) about an inch away from the engine. (This was done against advice, from those wiser than me in this forum)

However, what a difference! running smo o o o thly

However, I do have a harness on it's way from Germany ( gray market vehicle) that I will replace upon it's arrival.

Cheers, Bill in Boston