My e320 was running great. Let it sit a couple of days and it wouldn’t start. All electrical worked fine. Battery is less than one year old. I put a charger on it and the car started. Now it will only idle, 1000 rpm. If I press the accelerator it begins to surge between 1000 and about 1200 rpms. There is sludge under the oil filler cap but not on the dipstick. Oil change about 9 months ago. No sign of leaks but it is now about one quart low. Engine temp has always been steady at 80 now at idle it goes a bit above that.