1994 Mitsubishi Lancer misfiring when going up a hill

Check plugs for excessive gaps, check ignition leads and coil as well, start here.

Coil, this sounds like an ignition fault under load.

When a car misfires under load, such as your problem like only going up a hill, this is normally an ignition related problem, as you have addressed the first items that would normally be looked at, that being plugs and leads, the coil is the next item that would be of interest, but before replacing the coil, I would do a comp test just to be sure all is good there.

The engine is under more load in top gear, drop a gear and the revs increase less torque loading on the engine less load less chance of ignition break down. Basically the engine is straining in top gear, often called "lugging" you will experience pretty much the same thing trying to drive off in 3rd on the flat. The engine comps are extremely high when running, much higher than your cranking test, the ignition spark must jump the plug electrode and over come this pressure, the spark will always fine the easiest path to earth, so if the ignition system is under stress due to high torque loads, (lugging up hill) the spark will find an easier path to earth, hence the miss fire.

I think it should be compliant.

If there are only 4 leads from the cap, going to the plugs, the coil will be internal.