Well, that sounds like switch to me. We had another guy several months ago who had a similar issue and he fixed it with a new switch. Now dieseling is a whole different issue. BIGREDRASA is right about the hot spots (which can also cause predetonation) but dieseling can also be caused by timing, high idle, running too rich, and several other things. Doesn't sound like you have dieseling though.
That pink resistor will not have any effect on Pertronics as far as running when it's shut off. My petronics worked sorta OK, but nowhere as nice as the DSII conversion works. That pink resistor wire has more to do with coil and/or points than anything else anyway.
Just suck it up my friend, go out and spend some of your beer and cigarette money on a new switch and get it over with (while you're at it, be sure to destroy any "RAP" CDs you might have in order to remove any negative JUJU they might cause)

. Seriously, leave the switch wires alone and in OEM condition, at least until you can get the car running right. My old switch worked fine, but I replaced it anyhow during the restoration. So many functions are based on that switch that I didn't want to take any chances.
Its probably better that it keeps running rather than stops running as far as that Semi on your butt is concerned

!
Harry