Every M119 powered W124 has the wiring harness issues along with the Electronic Throttle Actuator. The harness should have a date code on it right behind the CAN box under the hood. If your date is 98 or later you should be good as its been replaced but if its earlier it will fail. Same with the ETA but the code for that is on a sticker that you can see if you remove the airbox. New the harness runs about 5-700 from the dealer and I highly recommend buying new and the ETA is somewhere in the $1500 range IIRC. Those can be found used but you must be sure you get the correct one for your car since the ASR/NON ASR engines used a different ETA.

I recently sold my 400E in the same color combo as yours and I really miss it. Its a very special car and its 80% of a 500E at 20% of the price.