Light switch at ~3000rpm!

[bear]

Recently (last three or four days), my 99 has developed a strange behaviour. Starts, idles etc, when taking off, it's really low powered and rough until around 3000 when it takes off like a rocket! So wondering if it's injectors. One might be leaking and there's not enough air till that Throttle opening. Just wondering if anyone has experienced similar problem, and if so, is it injectors. Follows on that if it is, then I need new ones or refurbish old ones!
Bear.