A bad TPS doesn't cause this type of failure. A bad fuel pump relay does however.
Since you're already in that far, replace it anyway. Did you remove the coolant passage block in front of the plenum?
Here's a link to the FSM
https://startekinfo.com//StarTek/outside/11883/PROGRAM/82380sl.html
Here's a useful set of pics of a 560sl going through the same thing you're doing. Make sure to replace all of the plastic injector housings, seals, pipes, injectors,etc while you're in there!
https://autotrend.activeboard.com/t43370554/mercedes-benz-560-engine-intake-manifold-removal-gasket-and-/