i removed the heads on a 3 valve 5.4 and reasembled. now it is pinging and no power. i tried taking it apart several times and realigning the timming marks cause to me it sounds like they are out. but they dont seem to be. i have codes for bank 1 lean bank 2 rich. the plugs when removed show the same result. do you have to reset the cam timming before or after? i tried a flash program to see if they would reset and a realearn and no luck. any ideas?

 

You're losing me.....reset before and after what?
Are you sure you have the o2 harness right-I've seen that exact same problem when somebody swapped the harness around on a reinstall and had the passenger side sensor plugged into the driver's side harness connection.
JL

 

5.4L needs to be timed both before and after head removal,You can start from scratch but have to pull the roller followers out of the heads as to not damage the valves. if you didnt though you could have valve damage. due to low clearances. i think you only have one tooth variance. any more than that and you will break stuff. the timing procedure is very specific. What did you do to time it?