One thing "I did learn from my self education on how fuel injection works is that the higher rated gasolines burn slower and thus deposit more carbon build up on the insides of the engine. I agree from another post that if you use some Cheveron Trecon fuel injection cleaner when you go to fill up again that will help clean the deposits on your exhaust valves and my add some smoother performance to your engine.
I also recomend having the MAF throttle body cleaned with CRC throttle body cleaner#599c Availible at PEP Boys , Cragen Auto Parts. A lot of junk goes through the throttle body and sticks to the high heat wire that measures the volumn of air the engine is taking in.
This unit can be disconnected from the air hose from the front of the car and spray cleaned and then reasembled.
alot of performance is losted because a mechanic neglected to clean the MAF sensor.Mercedes-Benz has there own version of fuel injection cleaner over the counter .
I hope this helps
Bob Geco
1992 300-E
1968 280SL
1987 ford Mustang LX 5.0 nothback