I got a new distributor cap and rotor set from Summit Racing for $23 and installed it today. The contacts on the old ones were corroded and eroded, so they definitely needed replaced. It idles much more smoothly now too.

New parts on left, old on right.

 

I'm surprised you didn't replace it sooner. Caps are more important than spark plugs!

 

I thought it had been, but it's looking like that wasn't the case. One thing I will say is that it runs a hell of a lot better now. It picks up and goes way better now too.

 

I have that same cap and rotor. Love it, I also did the summit 8mm wires and hypertech coil.