I have just recently done a head job on my 2001 ford f250 SD. I found that I had a leaking intake valve so I lapped the valves in both heads and re-installed using new head bolts and gaskets. Up on completion I timed it correctly with the crank mark @ the 6 o'clock position and the left cam at 12 and the right at 11. I even layed the chains flat and marked with a paint marker. But the truck seems really sluggish and has no throttle response at all. Any suggestions.

I was reading another post and some one said to put the crank key at 12 o'clock so the mark is @ 7 o'clock, Which is it the crank mark @ 6 or 7.