Ok heres what I got..I purchased my 95Z28 M6 about a month or so ago..I bought it missing a little bit...So I get home and have a local shop replace the plugs and wires with MSD 8.5mm wires and AC-Delco platinum plus plugs...It cleared it right up..(Fast forward three weeks later).Then on Christmas Eve I go to a gas staiton and fill up with 93 octane, and after a couple miles down the road from the gas station, the car starts to miss again just like it did before...Any suggestions??? Any help would be greatly appreciated...Thanks..

 

Not to sound too simple, but could you just have a bad fuel problem? Seems kind of weird to just start after a fill-up. You may want to add soem HEET and burn up that tank of fuel first.

 

run through that tank and try another station to fill up at and see if it continues

 

check to see if you have a burnt plug wire

 

Yep.. burnt plug wires are notorious on these cars since there really is no margin for error when routing them.
Unless you are running some monsterous ignition system 8.5mm wires are just downright ridiculous especially since 8mm will just barely fit into the stock plug wire clips. Have you looked to see if these wires have been routed in the stock location?
Your best bet would be to take them all out to carefully look to see if one or more are burnt.

 

I would definatly put some additive in the gas with ethyl alcohol, like valvoline water remover, or berrymans b-12 to get any moister or bad gas out of the system. If it is not missing too bad, run the tank out and fill with premium and see if the problem persists.

 

Yep - the 8.5 MSDs really won't fit in the factory routing looms. I had the same problem and it created a serious mis-fire condition. I ended up replacing them with Taylor 8mms routing them through the factory looms and that cleared up the mis-fire problem. I also changed out the crappy Bosch +4s and replaced them with some NGK plats.......