2007 XC90 3.2 low idle condition when braking in gear

Just recently bought a used 2007 XC90 3.2 with 95k Miles. When the break is applied while in gear (reverse or drive) the engine shakes pretty bad. If I switch it to park Or neutral, the shaking goes away. It doesn?t throw a code. My thought is a possible pulley associated with the cam belt or the timing chain. I would like to see if this is a common or known issue before having to pay for the diagnostic
found out it was the transmission's torque converter. Luckily it was already rebuilt and it was under warranty