Fire in the hole!!

Id like to check this out and maybe fix and kill this gremlin!

81 350, Starts perfect, runs at speed perfect but around town its still stumbling when taking off from a light or idle condition for more than 30 secs. temp stays at 200 +/_ in south florida where the outside temps are averaging 92 so I am pleased with this. I have a TKO 5 speed so in first no problem second she will load up and I have to back off to burn off the stumble? then ok until the next light. Timing OK, does not idle or run rough so I am looking for other reasons She seems to not burn everything at idle. I was going to EFI her but I am thinking its just going to do the same thing. Im thinking ignition, maybe hotter plugs? any Ideas would be great..

Thanks