Volvo Repair: T6 XC90 Acceleration Problem, volvo dealer, throtle body

Question
2003 XC90 T6, 30k miles -- I've got significant hesitation and surge under hard acceleration.  I've see two dealers to fix, first Volvo dealer installed software patch, second dealer replaced all plugs (said that engine was probably missing due to unusally high plug corrosion) and fuel filter -- still same problem.

I always use premium gas, keep car well maintained.  It seems to happen more in warm weather, could this be an issue with Turbo, injectors, computer? Any help will be much appreciated.  

Answer
Rick, since car is still under warranty and the dealer has not been able to fix it, then Volvo Tech services needs to be called.  Call the 800 number that you got with your car and Im sure the problem will be resolved.  It may be the throtle body recall that they have on all these newer Volvos.  Hope this gets you on the right track.  Roger