I have a 1984 944. I purchased the car a year ago and over time it became harder to start. I am confused because it seems like it decides on its own when it should start. One week it will start and then the next it will not. The longest it has not started was for 3 weeks and I tried every day. Then out of nowhere it started up. It seems like electricity is not always getting to the coil(new). What could cause this problem and how should I go about checking? Thank you for any suggestions.

 

Sorry, forgot to mention that it does turn over, just will not start.