I just got a s420/w140,has been sitting for a while,it needed 2 coils,after replacing those,I got a P0100 code,maybe the air filter housing is not seated right?,or MAF ?
It does have a lifter noise that kinda got better after driving for a day,maybe a engine flush will help,and what grade oil should follow the flush?,Thanks you for any advice.

For the lifter noise, you need to inspect the oil tubes that feed each lifter.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

check you engine harness for the old insulation that flakes off, this can cause several problems