[chevyn0va1]

Everyone gave you good points to look at but I didnt see what I think is most important, Check/change the O2 sensors. On my 99 I'm told there is 2 of them. Also replace your pcv valve.

And, as far as plugs go if you search my screen name you'll see I have talked before about plugs and what others claim. I however stayed with the motorcraft -with this thought, if they came with them from the line must be a reason.

I Personally called the company tech line that makes the +4's and I was assured the bad claims mentioned on this board are false.

You seem like a numbers type guy, have you thought of getting a code scanner that gives real time information? That could tell/show you a lot.