Car is missing and you can smell unburned gas pulled 3 spark plugs all black . . . no check engine lights are on and everyone has told me its probably the opti but i want to make shure before buying one

in gear idleing the car will shake and run bad for a while but every now and then it will stop shaking and run smooth this is whats throwing me off
it had been raining 3 or 4 days straight before this started so im thinking the cap could have gotten water inside it??? corroded or something any advice would help 94 Z28 lt1 automatic btw haha

 

In all seriousness though, it is hard to tell without knowing if there are any codes. Is it backfiring? You can set codes without throwing a SES light.

 

It's not backfiring just flooding leaves huge clouds of black smoke and its not the opti I changed it already and it made no difference although the bearing sounded aweful in the old one I can't find anybody around here to scan it and find out of it is throwing a code and I double checked and now I'm not even silkier if my SES light works