PLEASE HELP! 88 560SL losing power at 2500 rpm's

[RobManley]

I've sent one message out. I am hopeful that someone out there has had a similar problem. Mechanics want to start rebuilding motor one part at a time.
The power loss occurs around 2500 RPM's and only happens when you open up on the throttle.
In parked position, I reved the motor up to 2500rpm's and createda similar problem by pushing the plate in the throat open to let in more air. This causes the motor to stutter similar to when I speed up to 2500's under a load.
If anyone has had a similar problem, please respond. The car has had a fuel pump replaced, plug wires, plugs, rotor, and cap.
Does the fuel distributor govenor have anything to do with this problem? I feel like this is something simple, but finding simple seems hard.

Loss in Savannah! HELP!!!