Fuel or ? problem

[ringleader]

:Twist Need input on a problem I'm having with my 90 Vette 6 speed. When I take out from a dead stop in 1st to about 3000 and then shift into second and I'm at half throttle the engine seems to flatten out between 1800 and 2600, then it's strong again, the same thing happens at the same rpm in other gears. I have installed new injectors, new adjustable fuel regulator, new fuel pump and screen and the car has been tuned up recently.
Someone has suggested it might be the egr valve. Any suggestions would be appreciated.

 

[johnl]

:Twist I have installed new injectors, new adjustable fuel regulator, new fuel pump and screen and the car has been tuned up recently.

Probably you did, but, did you also change the fuel filter?