I have the Astra SRI on a 2001 plate, eveything is workin fine but my girlfriend sometimes complaining it feels like its going to stall, by this she means the idle speed is hunting and the lights dim then return to full brightness. I usually stick some VPower in and she's happy again. The car has done 92k miles now and wonder if there is anything I should do other then service it. Its been serviced every 10k - 12k miles and had a cam belt change at 80k I think. Is it worth replacing the battery, is there anything I can use to give the engine a good clean out?