steering feel like it lock up in a turn im guessing its the STEERING COUPLING SHAFT? should i try to lube it?

what plugs to run on a 4.7 H.O? i do like NGK


thanks guys

 

You can try and determine the issue by greasing it, but it will only be temporary. If you find out the intermediate shaft is bad, your best bet it to replace it. It is pretty simple if you remember to PB blast it for a couple days in advanced. You cannot put it on wrong due to notches in the output shafts.