Help identifying part

I bought an '82 380 SL that is in need of some TLC. I just put in a new chain tensioner (double row) and alternator, and did some general engine cleanup. PO was not particularly meticulous. I had the valve cover off, air cleaner removed, altenator out, and coolant tank loose. Car started very hard and ran very rough afterwards. Investigation showed what appears to be a vacuum or pressure switch dangling from a foot-long 2-conductor wire that comes out of the harness on the wheel well near the alternator. It has one 5 mm hose connection on the side opposite the wire socket and a mounting bracket with screw slot. Numbers stamped on it are 002 545 28 14 and 0 280111009. Can someone give me a clue what this part is, where it mounts and what hose it connects to. I have the MB CD, a Chiltons, and MB Parts Catalog L, but don't find it in these. Thanks.

You are looking at the mid-temp part throttle acceleration enrichment diaphragm. It mounts to one of the 3 screws holding the coolant tank to the inner fender. You will not find those parts in any MB parts catalog. They are part of an update that is addressed in a Service Info. There are a few more parts in it: the thermo-vacuum valve in the top of the intake, the green-red-white restrictor valve in the vacuum line at #6 intake runner, and a vacuum tee that goes into the manifold vacuum line along the intake. The harness that plugs into the diaphragm is part of the kit, it goes to the oil temp sensor down on the bottom side of the timing cover and the original oil temp wire plugs into it. I installed many of these mods 20 years ago! Just off the top of my head, the SI may be 07.3/1 but I am not 100% positive.

But I am positive that your hard starting and rough running afterwards has NOTHING to do with this! Check your cam timing.....sounds like the right cam [pass] is retarded. Pull both valve covers. Rotate the engine in the direction of rotation til the crank timing mark is at zero. Look at the left [drivers side] cam timing mark. Is it on top? If no, rotate the engine in the direction of rotation 360 degrees til the timing mark reads zero again. Is the left cam timing mark [the V in the washer between the cam gear and the cam bearing] exactly lined up with the line on the cam bearing? Hope so! Now look at the right cam. Where is the V? It should be JUST to the left of the line. Anything else means one or both cams are out of time.