JFLACO610

any1 know what engine code 24 means on my es250, i changed the valve cover gaskets, put it back together & now i got alotta smoke comin from the area under the rear valve cover, & the car is runnin shi!-y now, b4 this it was ok other than the leak. Engine code read 24. I also have what looks like black smoke out the exhaust, which didnt happen b4 either. Check engine light is on, BUT when I just about floor it it goes off. anyone? thanks.