boxster s flat below 4000rpm

[hillman700]

Hi all, had boxster for about 18 months and had very little trouble with it. its a 2000 3.2 s with 70k. it doesnt seem to pull very well below 4000 revs. when you go over 4k it pulls like a train. when you change gear and the revs go below 4k again it kind of bogs down untill it hits 4k again. if you change gear and keep the revs over 4k it flies!! ive cleaned the throttle body and changed the air filter. the cel light has never been on while driving and it has no codes stored. theres no smoke on accelleration and no strange noises

does this sound like a maf problem or a variocam soilenoid?? i dont want to guess at expensive parts that cant be returned so would be grateful for any info

thanks neil

[RFM]

It's recommended to read out the control boxes with a diagnostic tool first, a CEL light off does not mean that there are no codes stored in the control boxes. A possible error without codes, in case of lack of power in the lower RPM, are malfunctioning butterfly valves inside the black transverse intake tubes (between the L. and R. intake manifolds).