My check engine light came on during one of my warm up drives this winter. The roads were dry and clean but the outside temps were in the 16 degree F range. The check engine light came on but it was running fine. I put a can of Sea Foam in this spring and drove around and burned through a tank to let it clean the injectors. I then filled up with Shell Premium and have run about 1/2 of that through. I finally had it scanned at the local Auto Value store and came up with a diagnosis of a misfire and a bad O2 sensor downstream from the driver's side cat. I replaced that sensor and everything seemed OK except I am noticing a slight miss on acceleration and a more lopey idle than normal. After about 10 miles the check engine light came on again:

Back to the Auto Value store again and got this:

PO300 Random Multiple Cylinder Misfire Detected.
The guys at the parts counter suggested new plugs and wires. Car has just over 42,000 miles and has run perfectly in the past. Absolutely no chance of any water in the Opti. It has been fanatically maintained all of its life.
I bought the recommended AC plugs and plan to install them. I checked the Corvette Central on-line catalog and found the OEM LT4 wires to be quite expensive at about $160 for the set. Myself and the previous owner have tried to keep it all GM so I do not want to use aftermarket plug wires.
How do I test the existing spark plug wires to see if they are bad? I own a digital multimeter but the directions are missing. If I need to test the wires with this meter then how do I do it? I need the "Using the Digital Multimeter for Dummies" explanation please as I do not know an ohm from a volt or my arze from a hole in the ozone!
Any help is greatly appreciated. I have the car listed for sale on the Forum as "no issues" and "everything works perfectly". I want to fix it myself as I am a hands-on person and don't really want to take it to the local Corvette mechanic if I can avoid it.

 

Check your PM

 

Great! Thanks for the information! It is folks like you who make this forum the greatest!

 

strange story
i've got a lt4 engine too and it happends to me in March
same code + and other one (i forgot it )
in september i changed my plug wire but didn't put the GM LT4
I don't know why but after erasing a few times this code, he never same back

But if it arrives again what do you mean by "check your PM" ????

thanks

 

AGAIN NO cures posted lol WWHHYY man why?