98 Disco
Ok Here goes

I'm having a startup issue. Sometimes, becoming more frequent, the engine will crank and spin but not fire. When this happens I don't see any spark when i test my plug (screwdriver test). I can try for 5 minutes (turning the ignition all the way off and back on between attempts) with no luck and then for no reason at all the engine will start right up with no problem. Sometimes when it starts it sounds like crap but usually it just purrs like normal. I have replaced the plugs, wires, coil pack, crank positioning sensor, fuel pump, fuel filter. I THINK that removing the battery cable between starting attempts speeds up the process but I haven't been trying that long enough to know for sure.

Here in Kentucky the best answer I get from the good'ol boys is I should replace engine with a small block chevy... I can only assume there is an electronic problem somewhere but I've got no British good'ol boys in these parts. Seems like the battery trick resets something electrical but I'm absolutely no mechanic. Just a fix it guy

 

The replacements you've made are they new or used? Try unplugging/plugging the ECU connectors (box next to your windshield washer res). Removing the battery cable isn't a player with a 98, the computer has a nonvolatile memory so all the settings remain the same. Has the wiring up at the coils been messed with at all cuz the signal wires from the ECU to the coils are pretty important and each coil duo has them. You replaced the crank sensor which is the primary sensor for engine timing - spark. What did the wires and connectors at the sensor look like and those running along the block skirt? Did you notice insulation missing or a burned/melted connector throughout that run?