Question - Replacement Engine v. Replacement Throttle Actuator + Wiring Harness (1995 Mercedes E320)

Hi r/auto - a little advice please.

I recently bought an older Mercedes, and it's been a huge thorn in my side with constant repairs. Some further research shows that the wiring in these is pretty consistently crummy, and the throttle actuator and the wiring harness will likely need replaced. Total cost is about $3000 (aka, way more than the car is worth).

In trying to figure out repairs, I realized that rebuilt engines are far far less than that (around $800). So - my question - does anybody know if I can just replace the engine and call it a day? Does anybody have any experience on these?

Thanks so much.