TO check whether the timing is off:
(from memory, this may be considered a rough outline)
REmove acccessory belt
remove valve cover
remove spark plugs
apply a socket wrench to crank pulley,
rotate crank pulley until the timing mark on the pulley aligns with the mark on the oilpan, and you feel compression (with a gauge or your hand over the hole) in cyl 1.
THat puts 1 and 4 at TDC.
Now the ends of the camshafts have slots in them, they should both be lined up horizontally so that you could fit a straight edge through both at the same time.
(PS the slots are at the passenger side end of the camshafts)
Also see:
this thread for details about which timing mark to use on the crank pulley 
