1999 Chevy Cavalier Ignition? Crank Sensor?

So, I replaced my coil pack and spark plugs yesterday because my car is having issues when im idling and it will have trouble taking off or sometimes just cut off altogether. The check engine light has not come on and I was told it had something to do with the spark. So, I replaced both of the coils yesterday and the plugs and the car is still having issues. I can't hook it up to the diagnostic test and get a reading since the enginne light is not lit. I don't want to pay alot of money and get the dealer to look at it if I don't have to because im thinking that it is either the ignition switch or the crank sensor. Am I way off or do I need to spend the money for a diagnostic test at the dealer and then just fix it from there? I am trying all avenues as money is tight at the moment. Thank you so much for your time!