just posting this to help anyone who might have the same problem at some point. i had a simple problem with this van. driving home one day on the interstate it simply started misfiring and acting weird. but you could accelerate past the vibration and misfire and it would run fine in the higher rpm's. it threw the CEL (check engine light) and it was giving a code for a misfire on cylinder #2. it was also giving excessive fuel readings. obviously the two were related. i replaced the #2 COP and it was still having the same problem. anyways i did some research on this site and was very helpful. but i started at the simplest places first. i had read where some of the expeditions were having problems similar to this and it had to do with the plastic line that goes to the PCV valve. i also had read someone's about the MAF (mass airflow sensor) and another topic having to do with the EGR valve. had the plugs changed a few months ago but didn't have the cash at the time to change all of the COP's on the van. parts store quoted them at $40.00 each. very pricey. went on ebay and found a wholesaler in miami that had all eight brand new plus shipping for $104.00 what a deal! after i replaced them all i noticed the #7 and #8 COP's boots were very worn and flimsy. as it turns out when i replaced just these two she ran beautifully again and no CEL. i went ahead and replaced the rest and she's doing great! seems to be doing better on gas and everything. why it was throwing the code for the misfire on cylinder #2 is beyond me. it was definitley the #7 and #8 cylinders. in the process of having her torn apart i also went ahead and cleaned the MAF (two little diodes inside the air intake) with some electronic cleaner i use on PCB's. also check the plastic line from the PCV and it was fine as well. why in the world they use a fitted plastic line for that is just plain dumb. anyways i hope this helps someone who might be having the same problem. this is a wonderful site, and here's to looking forward to less problems in 2008. happy new year everyone!