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