Nice looking truck.....I have a 98 Expedition with 125k....have a misfire issue on acceleration....no check engine light however when I increase and prolong the acceleration check engine light starts to flash.....when I back off check engine light stops flashing.......any ideas to fix this? appreciated.....thanks and good luck with your offroading.
Bob - If you get the flashing CEL, a code reader should pull a code even if the CEL isn't staying on the dash. If it tells you a specific cylinder misfire, there's a good chance it's the coil pack on that plug (COP). I'd start with swapping the COP and maybe the plug while you're in there.
If it's not a specific cylinder giving you trouble, the next place to check are vacuum lines which are a very common issue after they get old and crumble apart.
I've fixed several vacuum leaks in mine and feel like i'm still chasing one down. I still can't seem to find the one that causes my AC to start blowing out of my defrost vents every now and then. I've looked through the lines/box by the battery and passenger firewall and all look good. I've cracked open my electronic climate control unit and replaced the little O-rings in there, which made it better, but didn't completely stop it.