Are you telling us that the car hasn't run for a year?i have a 1996 slk 230 auto i bought it with the problem im having cheap enough so hopefully someone can shed some light so far i have:
changed the cps
changed the k40 relay
all is good the car turns on the key it fires up then stops before idling when this happens the car shuts the spark off
when i got the car it has the 3 pin plug down on the drivers foot well looks like an immobilizer key hole ive traced the wires and they go into the alarm the problem came about when then battery went flat on the car a year ago and had the problem since.
any ideas i have browsed the forum and the have seen similar problems but not the same.
the car unlocks and tries to start on the key
If the alarm system is aftermarket, I would get it out of the picture and then continue troubleshooting. It sounds like something an alarm would do. Just to tease the thief