Heinz not had this myself, if however briefly touching the accelerator solves the issue it could be the throttle - effectively a variable resistor like a volume knob on an old radio. Like an old radio knob that crackles, perhaps some contact cleaner may help? I fear its a sealed unit on the pedal but it may help.
I recall Cain had a throttle body failure - I think it resulted in a full stop/break-down. Not sure if he had the same issues as you before it broke down completely. A good call to swap the TB I feel to see if it changes.
One other thing - I did have a similar thing happen once that turned out to be a less than tight battery contact - unlikely but just a thought.
