Recently swapped out my stock plug wires for MSD 8.5mm wires with all other stock components in place. Now the idle is rough, but the truck still has plenty of power. oh yeah 2000 Sliverado 4x4 Vortec 4.3 automatic. Any replies welcome.Should have I stuck with the factory 7mm wires?

Thanks for all of your help, thanks to the good people on this site I have eliminated many problems with my truck. I will work on this thing until I die before I would buy a foreign rice burnin piece of ****.
Please Help.[8D]

 

If all your connections are good, then you may have a bad wire. If it idled well before, try using one of your old wires and replace one wire at a time with the old wire till you find if one is bad. I can't imagine going to a bigger wire would make it idle rough.

 

I agree with smoke! In most cases, increasing the diameter will smooth out a rough idle, not make it worse. Check all of your connections, then go from there. Good luck!