Throttle lag after a deceleration/acceleration 2000 FI

[HAWKER]

I just drove my 82 Pininfarina to the FUN in northern Michigan from Chicago. We had a lot of FUN! I just had the engine rebuilt and she ran great till the last 50 miles. She developed a throttle lag problem. After lifting off the gas pedal from a high speed and then try to re instate the same throttle position, there would be a significant delay then the motor would catch with the snap of your neck. Additionally, when coming to a rapid stop from a cruise speed the engine would die. It would restart easily but the fun factor was gone with this problem. The probem seemed to be consistent and I am pretty sure it is a fuel delivery problem as she surely would have backfired if fuel was still being provided after a rapid decel and flameout. If I reinstate the throttle very, very slowly after lifting off the gas, she will struggle a little and then recover to normal. Any ideas from the gang?