1995 E320 CEL and codes 7,8,10
 

The car is equipped with the push button self diagnostic system.
After holding down the button for 3sec. I get 7 blinks, then 8, then 10.
I need some help with this.
Car started running rough occasionally. Felt under powered like running on 4 cylinders. It's progressively getting worse. If i put it in neutral end rev it over 3k it clears up and runs/idles smooth for about a minute then it's rough again.
Wire harness is updated.Had a recent tune up, new plugs and wires.
After some research I figured code 7&8 was IAT related, repaced it with a new MB part but didn't help.
I tried to self diagnose it but the service manuals I have are confusing and I have a hard time with them. Like one says to test ECU connector X, Y, for example at Idle with a volt meter but when I unplug the ECU connector the car dies. Getting frustrated at this point.
Anyways, all help is much appreciated.
Thanks!
-Pete