83k miles, recent buy, 1 week old to our garage.

Got a call from DW, while she was out on errands, slow drive then just before pulling into a store parking car starts to shake, she said a left to right and threw a CEL (I surmise bad idle) . After 20 min at the store she starts the car, still some bad but as as bad as it was with the shaking. Drives across to AZ, code is P0302, recommend she pours in a can of seafoam. Not much difference but CEL is gone but car is still shaky some.

Previous owner upgraded and barely drove this this car in the last 3/4 years. They replaced alternator at 60k + serviced tranny at stealer ship, new battery and coil packs 3 yrs ago @ about 78k miles, engine oil slightly over 1 year ago. When they decided to sell he drove it to work after it had sat for sometime. It threw a CEL, but went away after a day or 2. He thought CEL was as resultant from being parked, may be old fuel yada yada.

This is all the info I have. I won't get a chance to check it out until tonight or tomorrow. I am new to MB but wrench Camry, BMW myself on weekends. Again new to MB and have no idea where to start as I sit here. Any pointers would be greatly appreciated.