Hi guys, I hope some one may be able to shed there wisdom with my fault. I have a 2004 ml 270cdi just purchase. Very pleased with it but lol. When I test drove it no where to get it up to speed so didn't know it had a fault. So here's info on the fault and symptoms. Car starts up eagerly 1st turn of the key and settles straight away into clockwork smooth tick over.under normal driving I cannot fault the way the engine box performs smooth powerful no issues. I will make you aware of these two other faults with the car invade they have any bearing. Engine temp on dash didn't get to 80 deg c only about 75 deg c. Esp bad light on sometimes didn't seem to effect the cars driving. Back to the main fault. On the flat the car cruises at 70 or 75 I can't remember exact speed engine rpm is 2500 engine smooth no pulsing surging as you go onto an incline and there is a load the engine has a rhythmic pulse every few seconds the rpm fluctuates drops to 2400 then back to 2500 you can feel it doing it up and down every few seconds once the road levels out it stops. It doses this in cruise or on a steady throttle cruise off. The car has 165,000 on it so is just run in lol. I am having a gearbox service done next week as a matter of course because I don't know if it has been done. I have read this might be a cause as torque converter may not lock up if fluid level low or oil quality bad. I have also read torque converter solenoid/ switch can cause it. I am going to get it plugged in today and will post any fault codes later. I would love to get this fixed as the car is fantastic apart from the annoying fault at the speed you drive on the motorway.any help advise appreciated.