My 1989 300E has a starting problem. When I turn the key to start the car it cranks for a while and then starts but sometimes it will not stay started. When the car finally starts for the first 5 min the car has a very rough idle and I noticed that the rpm are very low and sometimes I need to have my foot on the gas to keep it from cutting out. After driving for a bit the shaking and rough idle goes away.

Please help!

Also a very stupid question. What size wrench would I use to remove the oil pan plug?

Thanks,

Fab