Spark plug wire diagram for 1997 gmc k1500 5.7 l

Hello,
My check engine light came on Saturday while driving. I have a 2000 GMC Sonoma 4.3L. I stop at Advance Auto to have it check and the man said the #6 spark plug was misfiring.

He suggested that I change the spark plug; which I did the next day ! Then the check engine light came on again, and I had it check. This time it show my #3 spark plug is misfiring, and I'm not sure what to do now ?

Do a compression test.

Check your timing chain.

Sounds like you have a couple of leads on the wrong plugs or in the wrong place on the cap.

What codes are stored? are wires all in good shape (tightly connected, not broken)? distributor cap tight and contacts inside good? Knowing the codes would be a good start in where to look for the cause(s) of the misfiring and shutting off. I had a similiar experiences a couple years ago. One plug wire was broken and caused it to misfire when it was raining. The code stored in the computer showed cylinder 2 misfire, which led me to search for caused specific to cylinder 2. Also, later I had my car just shut off while driving. I checked the distributor and one of the clips that hold the cap to the distributor was broken, causing the cap to flop around (and random misfires).
Hope this helps! :-)

Replace the fuel pressure regulator.

i think he is wrong ....check plugs wires and for vacuum leaks common for intake gaskets i have changed 3 this year and all had cyl misfire related codes

They are still looking for a cause because it isnt misfiring right now or because they cant find the cause of the stored misfire codes ?
If it is misfiring right now and they cant figure it out then perhaps you should find new mechanics !
I have seen a lot of bad coils on the PT.
Misfire is usually caused by spark plug wires first, spark plugs 2nd, and coil third.
If it isnt misfiring now, spray down the wires with water. If it misfires after that replace the spark plug wires and spark plugs and try again.
If it still misfires then the problem will likely be the coil.

When my check engine light went on, it was a oxygen sensor

good luck i have the same car and it has been a nightmare from day one . everything is expensive to repair mine showed a mis fire in same cylinder had to supposedle head gasket was bad and gas was gettting in causing misfire