Holley 1 barrel-huge dead spot

I've got a 76 Duster W/ a slant 6 and Holley 1 barrel carb and it will completly die on accelration right off idle unless you really baby it.It does however run fine after getting it going.
The carb is a rebuild from Holley and I've replaced the accelerator pump, fuel pump and fuel filter and no change Any ideas?

Checked your timing lately?

Yes-about a year back this car belonged to my girlfriend and she bought some"gas" that was mostly corn squizzins and it had pretty much had everything replaced and tuned to try to get it back on track and still the dead zone persists I guess I'll retry the timing -thanks