Pertronics is junk. I had one in my /6 car, and it would cut out around 4000rpm.
My suggestion, go electronic. Get yourself a 73 up elec ign distributor, and start from there.
Information on the upgrade is all over the web.
If that was your issue you likely had a bad part, or weren't sending the right voltage to it. I've run them successfully on several cars without any issues like you describe, including a Pertronix billet standalone distributor in my Challenger for most of the 60k miles I put on it. All I've changed in that time is the cap and rotor. Running an orange box ECU on the stock electronic ignitions can cause very similar issues, the orange ECU's are junk over about 5k rpm and start having issues even below that. And they fail like crazy. The stock electronic ignition is decent, but I wouldn't run it with a Mopar ECU anymore. Using FBO parts with the stock electronic set up is a decent way to go. I've gone to standalone distributers in all of mine though, getting rid of the ballast and separate ECU is the better way to go IMHO.
