I got a Ford Escort from 1988 1.3 which has a little problem.
Sometimes, out of nowhere (It can have been driving for hours or only for 5 minutes) the engine stops while i drive. It just dies and afterwards it's impossible to start again both with and without using carborater.
After an hour or two, it starts again.

I have been checking all 4 spark plugs, and they are fine.

What can be the problem?

 

check the battery cables and posts for corrosion. the corrosion can go under the cable crimps. Check all cable connections at the alternator. Check all ground contacts.

Check the coil, distributor and everything else related to the ignition.

Check fuel pressure. Check all wiring regarding the fuel pump.

Stop using starter fluid srpays because it will kill the compression.