I have a 2002 F150 with the 5.4. A couple months ago it started missing, usually around 1500 rpm. bout 3 weeks ago, I finally cot a CEL to come up. I had it scanned and turns out to be cylinder 7 misfire. Everything I have read is pointing me to replace the COPs. The interesting thing is, over the past 2 weeks or so it has started having problems starting. It usually happens in the early afternoons, doesn't seem to matter how long the truck has been sitting. The starter will crank, but nothing else will happen. If I let the truck sit for a while (couple of hours) it will fire right up. Once it's started it runs fine (or as well as can be expected with the misfiring). The first time it failed to start I immediately checked the fuses and relays for the fuel pump, once I pulled them and reinstalled them, the truck fired. I am now thinking that was just a coincidence, as that does nothing to help it start now. I have been told by a friend that it sounds like vapor lock, but I thought that was no longer an issue with the newer engines. My question is, do you think I have another probem or is it the infamous COP problem?

 

something else to mention, the mis-firing is sporatic. There are times when the truck barely wants to run, other times, it runs perfectly....any thoughts

 

Fix one problem at a time.
Known cylinder miss, fix it first.

 

You're right about it not being vapor lock.
It's one of the many advantages of fuel injection over carbs.

 

How long has it been like that? - if you go to long your PCM will shut down your injectors. I'm not sure to what extent or how long. Reason - to prevent damage to your cats.