Last weekend my Expedition 425 started to idle really rough and have a very noticible power loss. I was way out on the rubicon when it happened so I rode it for a while and it was back to normal. Then this weekend we went for a long ride and a couple of times it did it again. It starts fine and runs but once it a while it just seems to lose power and stop idling? Any advice is much appreciated.
Cammer

 

change your plug and your air filter first to see if that helps

 

My old Magnun (425) would do the same thing. I checked everything and could never find a problem. It had a new sparkplug, air filter, adjusted valves, vent line to the carb was fine, compression was good, it had low miles and I could never figure it out. The only thing I think it could be on mine (and I never had a chance to prove it) was the rev limiter. After a lot of research on this forum, it seems others have described the exact same problem and the cause being the rev limiter. I don't know much about the Expedition, but if it uses the same engine my Magnum did, maybe it has rev limiter too. If it does have a rev limiter, see if you can find the wire to disconnect it. The only other thing that could do it is something in the ignition itself (stator, trigger coil, cdi, coil), but it would be a bit of a stretch for the problem to be that intermitent (in my opinion).

 

To me it sounds like you need to check the old air filter......it might not be getting good air flow going through it....then I would check the plug...if you throw and new plug and have a good air filter in her...and your still having problems..then I would say it might be time to check out the jets in the carb.

 

I think if it was air filter or plugs it would run consistantly bad, it sounds like an electrical problem to me. Look your harness over for warn spots where wires might be shorting out or other bad connections i/e corrosion dirt in connectors, lose connectors etc.
also check you ETC to make sure the the cables adjusted correctly.

Good luck, these kind of problems are the hardest to resolve.