I have a 1992 230TE I have poor acceleration and on hills the speed drops off to around 40MPH. I have read the DIY section and have replaced the Over voltage relay, with no effect (I am getting voltage at the idle valve conectors). One very important thing is that the Idle valve has been disconected from the power cables. When you reconnect it, the car will start but will immediatly stall. I have talked to my local Mercedes Garage but they talk of checking the fuel pressure etc and ignore the fact that the idle valve has been diconected. I have replaced the fuel filter a couple of months ago. I think it must be an electical problem somewhere.