one at a time and make sure you mark em, that way you don't get lost
You should never need to replace the wires leading to the spark plugs. The 2003 Miata has a coil pack at each spark plug (inside the spark plug hole). The wires leading to the coils are low voltage and should never break down.
Depending on how many you crossed the engine would fail to run or run very roughly as the spark to the cylinder is not timed correctly
you would follow the spark plaug wires from the disributor to the spark plug and replace it. Spark plug wires are different sizes in length depending on where they go. Also make sure they are in the right order or your engine might run rough.
Incorrect timing, spark plug wires not installed correctly, timing chain worn out and has jumped a tooth, or distributor worn out.
You will not go wrong installing the OEM AC/Delco plugs, just like came in the car. This is what I would install in a GM vehicle.
I would replace the spark plugs after 50K, the wires and plugs again at 100K.
The cap and rotor would not be the problem as they are installed in preset position. Therefore the problem lies in one of two other possibilites: (1) SPARK PLUGS: Did you check the gap on the spark plugs? New spark plugs do not always come pre-gapped and it is always a good idea to check them. Spark plugs that are not gapped correctly will "miss" or "skip" and not give good performance. (2) WIRING: When you changed the plug wires, did you ensure you bought the right wires for your application? If the wires are not the right ones, you will get a "miss" or a "skip". Another problem would be the routing of the wires from the plug to the distributor. Did you remove all wires at once and maybe crossed up the order that they fit back on the distributor? Are the wires fit snuggly on the spark plug and the distributor cap?
you would take out the spark plugs still attached to the spark wires. place the metal of the plugs onto a grounded metal spot. make sure they are not touching in order to prevent damaging them or blowing fuses.
No, not unless your connect the plug wires wrong or one of the new spark plugs was bad.
There is to much heat from the exhaust manifolds. There should be medal factory heat sheilds bolted to the exhaust manifolds to pervent this from happening. INSTALL HEAT SHEILDS
Probably the spark plug or spark plug wires, I would try that first.
Yes, check the connection to the starter and the spark plug wires first and replace if needed.