2004 XC90 2.5T Intermittent Overboost only w/Cruise Control On

[dtarullo]

I have a 2004 Volvo XC90 2.5T with ~121xxx miles. We were running on the interstate at 75mph with cruise control on, when we ran thru a dip in the road surface, which was enough to jar the car upward, and at the moment we hit, the cruise shut off and the power dropped to the 'reduced engine Performance' mode and could not hold any speed. Cleared the road and after shutting-off the motor and restarting, the car ran fine, until on the return trip under same circumstances - 75mph w/cruise on, hit a dip in the road and the message center again read 'reduced engine Performance' mode. I cleared the problem the same way and continued driving. Completed the trip without using the Cruise Control (several hours more highway driving) and did not encounter the problem again nor over the week since – have not used cruise control since that trip. I scanned the ODBII using my CarMD scan tool and got the secondary code P0234 (Turbo Charger Overboost Condition) with a description saying it is an intermittent problem. Fyi, recently had the full timing belt job completed. Does anyone have any insight on this issue? Any ideas on what the cause could be would be greatly appreciated. Thanks