I've noticed a noise coming from the bottom of the passenger side footwell. It's a low pitched whirring noise but can be heard easily above the engine noise. When I start off it gets louder and then drops back when I take my foot off the accelerator. The cabin and dash lights seem to flicker in tune to it. Yesterday then when I accelerated fairly hard out of a roundabout the engine management light started flashing and when I start it now it is very lumpy and jittery at low revs. The car is on about 99,000 miles. I was about to change to a GTA clutch solid flywheel and quaffe diff, so I'm hoping it my be related to the old clutch or dual mass flywheel and not something more serious. Would anyone have any thoughts on what it might be?