Looks like port side cylinder head temp sensor.
Injectors? Merc lists them for $750/set. Serviced for $120/set + shipping. Some parts prices will scare your pants off. Throttle position sensor $550. About 5 times more expensive than Mercedes. Ebay can be a lifesaver, but some sellers are listing parts at 75% of new. For 20 year old parts.
New parts can be ordered thru any local Merc dealer. Or online Merc dealers. Google it.