Lack of power below 2500rpm
 

Help - my 2000 SAAB 9-5 auto runs like a dream from start in the morning but as soon as it warms up it lacks power from pull off up to 2500 rpm then it boosts and goes as if nothing wrong.I know the auto doesn`t get off the line as quick as the manual but this does not feel right. I`ve recently purchased this car so am not very familiar with it . Any ideas?