Taking pictures of the motor,don't worry no one is stealing motors.
Putting a rag in the tail pipe,COME ON,maybe try it if you want.Rag will pop right out when you hit the gas or it will burn.
Coat hanger!!!!
Some one who messed some thing up cause they did no know their stuff,OK NOW
I work in a CAP station in San Diego doing repairs and I feel most places are honest.Down here only a few places do Mercedes,BMW,Jag ... CAP repairs. I know because we get most of them.
Changed a coil on that 400E,sounds like a shop that is pretty bad.car drove in on eight cylinders not four.
Maybe smog dude touched a bad wiring harness but even that sounds wrong.I know lots of bad shops but only cause they are not very good at what they do not cause they sabatage cars or steal stuff.
So has the car come back to life?Looking at those readings this car must run pretty bad.Is the wiring harness new or O.E.? Too bad you are so far away,looking in person is the best way to handle this problem.
Maybe look where they had their hands under the air cleaner to see if anything is unplugged.
Oh,these cars are dyno'd if they don't have trac. control
Rich

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88 300E White, sold 9-04
88 190E Black 2.3 sold
90 300CE White, Grey sold 12-24-04
92 400E White,Grey Sold 5-06
90 300CE 91K Signal Red,Black Sold 2007
1989 300CE Smoke silver,Tan Sold 1-08
1993 300E 3.2 M104 motor
1991 300CE White,Grey
1994 E420 beautiful car,gone to new home
1994 E320 Smoke an Parchment.Beautiful car