Ignition is usually the easiest of the three to check because on most engines, all you have to do is pull off a plug wire and check for spark when the engine is cranked. On coil-over-plug DIS systems, there are no plug wires so you have to remove a coil and use a plug wire or adapter to check for a spark.
Stress can affect every part of your body. muscle aches, head aches, how your hair grows, the texture of your skin, it can affect your menstrual cycle.
Stress hormones like adrenaline and cortisol have effects on the nervous, endocrine and immune systems of the body. It is thought that adrenaline and cortisol suppress the natural killer cells function and reduce their ability to assess the body for abnormal cells, making people more susceptible to viral infections.