A month ago I posted a thread about my 4.5 LCF using coolant and puffing white smoke. I followed the advice of most members to check the EGR cooler first . Since no ready made EGR delete kit seemed available I decided to block the EGR cooler (the 6.0 block off plates are the same diameter) and I'm happy to say that (although I've only driven 100 miles since its been back together) its no longer smoking, losing coolant and so far no check engine light. The truck ran fairly strongly until yesterday when I changed the oil. The previous owner used motorcraft dino. However since napa was close and having a sale I bought 4 gal. of valvoline 5 40 synthetic extreme and used one of there 7214 gold (Wix) oil filters. Now the truck seem to be missing , surging and down on power. A small plastic button fell off of the top of the latching return tube that the filter goes over, I fished it out of the filter housing and put it back on top. Anyone have any ideas what could be causing the poor performance , the oil ,the filter , the plastic button that popped out, a loosened wire or plug?