Hi,
Disconnect your battery neg for at least 30mins. Then you need to drive carefully for about 300 miles so that your ECU can set itself up with normal driving. It will then respond better when you call for power.
Good luck.
When the ECU is reset on any car it defaults to 'safe' settings so that it doesn't damage the car. They then learn the optimum settings to give best performance over a period of about 2/300 miles. If you are constantly ragging the car during this period it will set it's average settings to expect higher revs. The result is no performance at low revs, average performance at high revs.