2000 blazer 4.3 new plugs and wire (changed them 2 times) new coil new plugs and still have arc all over witch is making a multi misfire WHY

Question edited for clarity. Full year make model in title and mis-spelling of 'misfire'.
Question moved to sub category.

The misfire code only tell you that, unfortunately it doesn't tell you why. When swapping parts to test theories, only swap one thing, one cylinder to one cylinder and only one item, the coil, the plug or the wires, not all three. What was the make of the Crankshaft Sensor? Only buy quality OEM replacements as there is a history of bad ones from Mexico and China.

Wouldn't hurt to check the wires again. This has a neat diagram.

https://www.silveradosierra.com/threads/5-3-firing-order-cylinder-diagram.734633/

..

multi misfires can be from injectors --dirty and not squirting properly or low fuel pressure ---fuel pump or dirty filters
plugs are only half of a misfiring problem and the injectors are always left out
Next time include all details like make, model , year of car in your question to get a better answer

Change the spark plug wires.

For the misfires, start by pulling your plugs. They either need to be cleaned or replaced if questionable. Then, you may have a bad coil or coil pack. You can test them with a multi-tester-you'll want resistance values that are specific for your vehicle. Alternatively, you can switch the coil packs around (if you know you have a good one from knowing which cylinders are misfiring and which are firing o.k.) If your misfires change cylinder numbers from swapping, you know you had a bad coil. Other possibilities for misfire could be the electronic ignition module or the pick-up coil inside the distributor(if you even have a distrib.)
FYI: code for o2 sensor means that circuit has a malfunction, may be the sensor itself, or a wiring problem. Good luck.

Hello mikew564.The first diagnosis was number 2 or 3 cylinder not firing. Once you changed the coil, the check engine light went off. When the light came back on again, did you get it diagnosed again to find out if the problem was the same?... 2 or 3 cylinder not firing????

First of all, there is NO extra wire/ground on the coil/ignition wiring (see images below). The spark plugs and ignition plug wiring can be checked for arcing, corrosion, resistance and can be checked for cracks in the insulators or worn electrodes (and spark gap) by a competent mechanic.
If you are having the same issue (2 - 3 misfire), there are several techniques for eliminating the plug wires or spark plugs. Spray water on the plug wires to see if they are arcing. Swap plugs from cylinders 2 & 3 with cylinders 1 & 4. If you still have a 2-3 misfire, check/inspect/examine the coil connector pins & coil harness to the coil(s) themselves.

you have a single 3 or 4 pin connector to the coil pack. Someimes the wires get corroded and break off at the connector. Ford has a pigtail kit to fix that issue. Usually a misfire with the check engine light on.

Green/bluestripe is from ignition switch

Black/green stripe is to PCM (computer)

Black/orange stripe is to PCM

These last 2 wires are what the PCM uses to fire the spark plugs 2 at a time.

most likely a coil on the plug.You will have to unplug one at a time to see witch one is bad.When you unplug one coil,and no change in the idle,then that will be the one that is bad.

try a new crankshaft sensor not hard to change 2 bolts and a wire

have you changed the ignition wires? perhaps firing order crossed? if not coil pack or ignition wires faulty how do you know it is not "FIREING" on 1 & 4 have you tested it with a spark tester tool???