The missus came into work today after driving to and from bathurst, with the engine making a heavy clunking noise that sounded almost like a spun bearing on the crank but slower than engine rpm and from the top of the motor not the bottom. It was almost like a valve was hitting the piston so I told her to take the car home and not drive it. When I got off work I started the car and there was a loud tappet rattel for a short time but no clunk that I heard earlier and no other strange engine noises. I havent been game enough to drive it in fear of further damage but the noise I heard was from the front of the engine and sounded to be from the top end. Car is 94 ef 5.0l auto with 191000k's. Any ideas

sounds like maybe a lifter, rocker, bent push rod, or valve has let go. i have had all of these happen on other makes and models of cars.
u need to take the rocker covers off and have a look see whle some one turnes it over