I just had plugs and wires changed on my 97 F150, 4.6L . Plugs were changed at 100k but never had wires put on it. It now has 177k and has always run like a top with no problems. BUT... after the change, I have noted that it now starts much better even though I hadn't even noticed that it didn't start as well before the change.
One thing though, when I ordered the Motorcraft wires, the supplier substituted the #5962 with #5934 and related it was replacing the 5962. The 5934 are listed for the 99 model 4.6 so I thought "no Problem". Upon replacing the wires, the mechanic I used, just matched each one as he replaced them and ended up with two wires that were about a foot too long! He routed them to take up the slack but just wondered if anyone else has run into this? No problem with it all but just a little strange.
Last week, I installed an Airaid intake kit and noted a much lower idle RPM for a day or two. I was told my my mechanic friend that the computer had to adjust for the change and it would be ok. Sure enough, it has and all is well....
These 4.6 surely are some dependable engines, as I have one with 177k and another with 156k and both run like tops. Good work, FORD.........