P0301 Mercury - when it starts to misfire, I can turn off the overdrive and it stops, why?

Question

2006 Mercury Mountaineer - code says Misfire cylinder 1- changed plug, coil, fuel injector already. When it starts to happen (usually under an increased load condition -hill, increasing speed) I can switch off the overdrive and it goes away. Why? and what could the problem be?

Answer 1

P0301 Misfire number 1 cylinder

To get to the solution for this remove the coil of number 1 cylinder and sparkplug of number 1 cylinder and move it to a differenet cylinder. You will also need to rule out mechanical condition by doing a leak down test and a compression test of cylinder 1