When you remove the intake manifold, note the position of both knock sensors. The new ones must have the wires coming out in the identical directions as the old ones.

You do not need to remove the injector rail from the manifold. I suggest keeping the injectors in place, just loosen the fuel lines at the top and backside of the block. Then flip the manifold up, out of the way. Should save you at least an hour of additional work.

Also, when you remove the bolt for the dipstick on the manifold, remove the bolt for the manifold bracket which is right next to it. When reinstalling, do not tighten down the manifold bracket bottom bolt until the top bolt has been secured.

Klaus
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Common sense trumps a PhD