1989 f250 with a 351w ran fine with the check engine light on now it is off and it idles extremely rough and misses

take it and have the engine codes ran that will tell you whats up with it sounds like a bad spark wire or coil but could be something else

Check for intake manifold vacuum leaks. Spray around the intake with a can of carburetor spray and if you hit on a leak the engine idle will change.

Driving around for a couple days- is one thing

Not caring at all & driving for weeks with a check light
on,hope for the best & no damage or at least something
you can afford

Low oil level by a few quarts,really,how's that possible?

Sounds like you might have gotten some bad gas, Try a bottle of HEAT. good luck

Check fuel filter?

sound like its missing
check sparkplugs wires and coil pack for fire if not that run a compression check

Hi shoemaker.
Fuel filter issues show up in high demand fuel needs such as passing or going up hills. Rarely do they cause rough idle problems.
Is the check engine light on or flashing? A flashing light indicates engine misfire and should be repaired as soon as possible.
So you could have a vacuum leak, a stuck EGR valve, bad ignition coil, worn spark plug, and many other items.
If you don't have a check engine light and haven't done a tune up do one to eliminate a few items and see if that smooths it out.
If you have further questions ask me and I will check and answer you.

KL

change sparkplugs and wires

Bad fuel, water in the fuel, dirt in the fuel.

Drain the fuel tank completely.

Pour in a gallon or two of fresh fuel.

See how it goes.

Put some of the old fuel in a glass bottle, hold it up in front of a light and see if you can see any foreign material in it...

map sensor. check your spark plugs, wires, etc. maybe a loose wire plug. did u mention check engine light, i wonder can you tell me what diagnostic code came up. go to ur nearest auto parts if u dont have a scanner. and pull them codes out.