I drive an 04 f150 fx4 and it has a little over 150,000 miles. It randomly started shaking extremely bad. when i am driving there is no shaking at all but when i start breaking and slowing down the shaking starts. when i am at a complete stop the shaking continues. when i put my truck in park it stops. I got out and looked under the hood and there was oil all over my engine. i cleaned all the oil off and noticed there was a hole on the passenger side valve cover where what looked like the timing chain was showing. I haven't drove it since and trying to figure out what is wrong and how much it will cost to fix.