OK, you have dug yourself into a hole by making adjustments and changing parts without any real diagnostic work.

By turning the screw in the mixture adjustment tower, you either leaned or enriched you mixture. The car will not start if you are outside of the systems parameters. In the future, take notes (written) of any adjustments or changes you make.

You are in a situation with a few possible outcomes:

1. You can bite the bullet and pay a professional to fix it. This may be costly, and your tinkering will not make his or her life any easier. If you can afford it, you should go this route, especially if you need the car any time soon.

2. Or you can read everything written on this board about the KE-III system and figure things out yourself. You need to abondon your current approach, known as "shotgun repair"- that is, throwing parts at the thing in hopes something will be the cure.

Start researching posts on mixture adjustment, fuel pressure, electronic control, airflow meters, EHAs etc. Everything in the system must work in harmony for your car to run properly.

There are some real experts on this board. Read through everything they have written about this system.

To get started:

Go buy the sears multimeter if you don't have one. Should be $30.00 or so.
Your car has the KE-III system. Also known as CIS-E.
Read relative posts by stevebfl, duke2.6, brewtoo, and others who know what they are talking about.
Please stop making adjustments if you don't know exactly what you are adjusting!

Good luck.

__________________
'90 300SE 298k
-300K and it gets put into retirement.
'80 300D 255k Purchased new by family in 1980.

Had a:
1973 220 (gas)
1980 300SD
1992 400E