[tycapps4]

I recently replace my valve cover gasket, and ever since then my car idles around 400 and shakes violently. sometimes it stalls completely. The car does not accelerate as fast as it used to, also if i am in a high gear at a low speed, it used to steadily pick up speed, but now i shakes and feels like its going to stall. i tighten the spark plug covers and made sure the maf sensor was plugged in. Check engine light is on. please help!