Hey guys, I recently inherited a 99 Expedition 5.4 with 90k miles. I'm trying to fix it up so I can sell it. Like the title states, the truck runs rough but there's no check engine light on. I did some research and ended up replacing the PCV elbow and that made it run better for a while but now it's back like it was. It won't die, just a really rough idle and a miss while driving. I imagine it's probably a (or a few) coil pack(s), but I have no way of knowing which one(s) to replace. I would think that would illuminate a CEL though. I'm also having problems with the AC. Upon inspection, I found that the compressor clutch assembly was completely gone from the front of the compressor. I replaced the whole clutch assembly, then voided the system of Freon and refilled it to spec, still no cold air. The compressor clicks on and off like it's low on Freon but it can't be. I'd just sell it as is but in south Louisiana a working AC is a huge selling point! Any insight would be appreciated. Thanks in advance!

 

Maybe you have the original plugs? Ask if they were ever changed. Motorcraft plugs are good for 100k, mine went bad at 97k.

 

You need a code reader that can read pending codes. That will tell you about the misfire.