Hi guys! I have this 93 W124 300E 3.2 motor. Owned and loved it for more than 10 years, now it belongs to my wife. So here we go. First it have a problem with the idle, when in park sometimes rpm are just jumping ftom 800 to 1500 all by itself and now when she drives it for more than 25 miles, so car gets nice and hot something gets cut off, engine starts to shake like crazy, and speeds go down to 30 mph and wont get any faster. She drove it home tonight and motor was not running normal. I tried to shut it off and then immediately restarted and it was running normal again. I have no idea and I need help.
Please advise.
Thank You.