Thanks for the reply. What I mean by a flat spot is when the car shifts from 1st to 2nd under full throttle which is at about 6300 rpm I notice a distinct softness in acceleration in 2nd gear for about the first 500-700 rpm then it takes off like a scalded dog up to the rev limit.
I had another friend with a 92 500E with no chip drive the car and he definitely noticed what I was talking about. It is hard to describe.