Fitech issues

I have a 440 that I put the FiTech EFI on last year. Just recently it has started to stumble and cut out under full acceleration at an idle. If I ease into the throttle at maybe a 2 or 3 count before peddle to the floor, I takes off fine. Don't think it could be ignition issues cause it only does this from an idle and no other time. I'm not using it as a timing control and I've rechecked the IAC and throttle postion and it's all good.

Any ideas would be great.