I have a 92 jeep cherokee xj. earlier i went out to grab some lunch and i cranked it and it idled very rough. like a jerking/shaking. i turned it off to crank it again and it will crank but will not start. after trying that i saw a little bit of smoke coming out from under the hood. and it wasnt much smoke at all. i tried to crank it again about a hour later and it still start. I need help what could it be??

 

Sounds to me something with fuel. What color was smoke? Smell? And have you done anything to it lately?