Pinging/Vapor Lock?

Ok ladies and gents!! Got my dart 360 running again. Swapped cam with a 292 mopar purple cam advanced 4° @ crank and has an fbo distributor with 15° initial and 34° total. Victor 340 intake 850 thermoquad with fatter jetting came off of a drag 440 cuda according to seller. 3.91's out back. Runs pretty well for the 1st 30 to 45 minutes in humid to warm weather about 94°F 1st time out. Then if I get on it it sounded like it pinged slightly not too much but anyway I let off immediately and just feathered throttle. Starts fine not hard starting but idle does get dirty when run for a while. I did accidently put regular gas which has about 10% ethanol and then I added a lucas octane booster but didn't seem to do alot. Car used run well with 93 octane but still had ethanol. Please any ideas to rid pinging?!