the problem with 231 is it seems to have a mind of it's own. so does 232. i've been doing volvos, along with bmws and mbs, for about 20 years. i have the factory manual and have NEVER found a cause for 231/2. pull the fuse for ecu, #4, i think. this will clear the code and resets the adaptation. i've had this work a few times on cars that are otherwise ok. once you try this and the hestation persists, have some one diagnose it. it may be in the ignition system-cap, rotor, wires, bosch platinum plugs-that's causing the hesitation. the lh2.4s are not that smart, code-wise. so looking at the code for the hesitation probably won't give you a clue. good luck, chuck.