98 expedition, surging at idle, check engine light on.

okay so heres a complete description. The car started surging at idle, eventually the check engine light poped on after a few days, i checked oil, it appears to be way low, even though ive had an oil change about 2 months ago or less. Checked the coolant reservoir, and the water level was normal, however it was pretty dirty, and after draining there was alot of sludge stuff in the bottom. Not sure what it is, thought it was maybe oil, however shouldnt oil float to the top? upon looking at the oil dipstick i did not notice any odd coloration or residue in the small amount of oil there. Guess ill have to drain it all out to really check.
No smoke in exhaust, so im ruling out any water in the oil though.
Will check codes tommorow, but thought id see what you people had as far as opinions now.

I poped a quart of oil in, to see if the check engine light would vanish.. it did not. But maybe it needs to be cleared first? After flushing and refilling radiator, and adding a quart of oil, i ran the car for a little while in the drive way, and it appears to still be surging, i did not drive anywhere but just let the car idle in park.

That seems like alot of detail, hope someone can get some idea from it.

Thanks:banghead:

Also after draining i checked the bucket for oil, and although there was sludge i saw no rainbowishness, or any seperation of oil at top, only black sludge in bottom. However after refilling reservoir, i did notice tiny microdroplets of oily substance, ontop of new clean water, not sure if thats normal or not. Just praying its not a blown head gasket lol

anyone, anyone at all?

I have a Lincoln LS that was doing the same thing and it was the Coil on plug, (COP). I don't believe that low oil will set the check engine light. I'm not even sure that the Expedition has cops. If you have access to a scan tool or go to auto zone they will check the codes for you. It should tell you the problem. If it is a coil it should tell you what cylinder is at fault. Good Luck

Did you ever get the codes? Expeditions are known to develop a vacuum leak from the hose that attaches to the rear of the intake manifold. This will cause surging and a code thrown. The rubber grommet that leaks is a dealer item and simple to repair once diagnosed.