Don't change any parts till you get the car tested hot.Those numbers are from a cold cat.That is why the 25mph test is so much better.
I work as a smog tech for a cap shop.
Do not change your cat unless it is broken,use only direct fit o2 sensor if you change o2.NO GENIRIC 02 SENSOR.
Bring car in for a new test and sit in the car with the motor running at about 1,200 rpm.
Car will pass no problem.If a cap shop works on it you may end up with a geniric cat converter,which may only pass one time,as in replace cat at each new smog. If car fails hot then at least you will have correct fail numbers.
All the Mercedes I smog at work will pass hot with maybe only a new Mercedes 02 sensor
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