What would make my check engine light come on then iddle rough then wont start

CEL/SES On

What you need to do here is have the computer scanned for OBD2 codes, there's a problem within the engine management system that caused the light to turn On, this is your starting point of diagnosis

https://www.2carpros.com/articles/car-cranks-but-wont-start

Next time it refuses to start don't wait for it to make up its mind-do below immediately to determine if its fuel or spark problem

Get a helper disconnect a sparkplug wire or 2 and ground it to the engine atleast 3/16 away from ground-have helper crank engine over-do you have a snapping blue spark? If so-you have a fuel related problem, Do you hear the fuel pump come On when you turn key on? If not check fuel pump fuse and fuel pump relay if okay-check the fuel pressure to rule out the fuel filter/fuel pump/pressure regulator and listen to the injector/s are they pulsing or hook up a noid light. No snapping blue spark continue to troubleshoot the ignition system-power input to the coil/coil packs,coil's resistances,cap and rotor,distributor pick-up coil, ignition control module, cam and crank sensors and computer Note: If it doesn't apply disregard it and keep testing

I've checked Mit1 and you don't have the inertia switch-my advice is check the wiring connector that are visible and make sure its firmly connected