I recently started my truck (2000 4.7) yesterday and found that it didnt feel right. it started to shake. it was very noticable. i put it in drive to see if it would go away but it became worse and the check engine light started to blink. pulled it back into the driveway and had a buddy come over to see which code it was throwing. P0300(MCMIS)/P0303(cy 3)/P0306(cy 6)/P0171(fuel too lean Bank 1). So i began to switch out the bad coil packs to double check it was throwing those. when doing this i noticed a clicking noise that I had never noticed before. My buddy said that it could mean my valves need adjusting. the truck has 160,000 miles on it. i bought it used and dont believe its had any adjusment done to it. I had this problem happen before when driving on the freeway. And it turned out to be a bad coil pack. that was about three years ago. just wondering anyones thoughts on this. should i replace all the coils or spark plugs? not really sure how to diagnois to see if it is the valves or not.