it could be that the timing is a little off check the timing with a timing light, it could also be the ignition module which is very difficult to test on your own you can take the module to advance auto parts and they can test it for you!
On older cars it would be replacing, PCV valve, spark plugs, plug wires, rotor, condenser, and possibly distributor cap. On newer cars it usually means replacing plugs & plug wires.
No, not unless your connect the plug wires wrong or one of the new spark plugs was bad.
Worn spark plugs would cause mis-firing or non firing cylinders, both are no good for the engine, replacing the plugs may stop the knock (Could also be a different problem) But you should replace spark plugs as soon as possible.
I would start by replacing the spark plugs and plug wires. If that does not fix the problem seek professional help.
Have vehicle scanned to determine problemv and/or clear codes
Because you didn't change the rest of the ignition system. Plugs, Wires, Rotor, and Cap are a must for ICM replacement.
the engine is constantly vibrating and it dislodges the spark plugs
fuel filter clogged or plugs, wires, rotary button and distributor may need replacing failing fuel pump -- mine did this and soon failed
Possibly one or more bad glow plugs. try replacing your glow plugs.
There would be six spark plugs for a six cylinder engine. One for each cylinder. Unless it is a diesel, then there are no spark plugs.
Assuming this is the 4.3 engine, minor tune up consists of replacing the spark plugs, air filter and fuel filter. A major tune up would consist of replacing the spark plugs, spark plug wires, distributor cap, rotor, air filter, fuel filter and pcv valve.
That would depend on what year of Ford Ranger and what size of engine it has