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.
The nervous system regulates the homeostasis of the body either directly by sending messages to various parts of the body, or indirectly by relaying them via the hypothalamus, the pituitary gland, and other endocrine organs. Reaction to stress is particularly complex and affects many physiological mechanisms.