Misfiring after replacement of spark plugs and wires

Could be the HT leads are at fault.

Does it have spark plug wires? If so, check top make sure one isn't grounded or resting on another spark plug wire. If coil-on-spark plug, check for bad cam sensor... Does computer bring up any codes?

Usually, if you only have 1 cylinder misfiring, you have either a bad spark plug or bad spark plug wire. If you replace the cylinder 6 spark plug and still have a misfire condition, replace your spark plug wires. If replacing the plug and wires doesn't fix the problem, replace the ignition coil.

I’m happy to help further over the phone at https://www.6ya.com/expert/jeremy_69f3cc28d95bf514

Do a complete tune up.. Spark plugs, wires, distributor cap, and rotor button... If it has coil packs that sit on top of the spark plugs.. Replace the spark plugs and cylinder number one coil

Possibly bad spark plug wires.

1. Bad or fouled Spark Plug at #1 Cylinder.
2. Bad or misfiring Wire going from the #1 on the Distributor/Electronic Ignition Coil to the #1 Cylinder.
3. Misfiring at the #1 on the Distributor/Electronic Iginition Coil.

a. Unplug the #1 Wire at the #1 on the Distributor/Electronic Ignition Coil.
b. Using an Auto electrical testing: Probe, wire and ground clip electrical, stick the Probe into the opening at the #1 Distributor/Electronic Ignition Coil. Use the grounding clip - clipped to a portion on the engine.
c. Start the Vehicle and check for rhythmic spark.
d. If there is NOT rhythmic spark, the Distributor/Electronic Ignition Coil needs to be replaced.
e. Turn off the engine.
f. If there is rhythmic spark: Reconnect the #1 Wire at #1 on the Distrubutor/Electronic Igntion Coil.
g. Disconnect the #1 Wire from the #1 Spark Plug.
h. Again using an Auto electrical testing: Probe, wire and ground clip. Insert the Probe into the end of the #1 Wire and clip the ground clip onto the engine.
i. Start the engine again.
j. Again Check for rhythmic spark.
k. If there is NOT rhythmic spark the #1 Wire needs to be replaced. (Replace all Wires as a Set).
l. If there is rhythmic spark then the #1 Wire is fine.
m. Turn off the engine,
n. Remove and Inspect the #1 Spark Plug. Clean if necessary and Regap.
o. Reinstall the Spark Plug and reconnect the #1 Wire.
p. Restart the engine.
q, If the code reappears:
r. Replace all the Spark Plugs.
Let me know if this helped or if you have additional information or questions. Feel free to contact me at FixYa.Com.

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.

It if is misfiring on one cylinder. The replace the plug wire first. Make sure plug is good.
If two cylinders are misfiring, then you will want to replace the cap, rotor, or coil pack depending on what you have.

A typical tune up includes spark plugs, air filter, fuel filter, spark plug wires, distributor cap and ignition rotor. You must determine which parts are needed before you start.
I would suggest to first check spark plugs and spark plug wires.