Since the car was in dry storage for some time, I'd be willing to bet that the delivery rack in the injection pump is stuck. The way to check it is to remove the 10mm cap screw at the front of the pump, thread in a long, thin bolt and try to move the rack back and forth by hand. If you can't, it's frozen. This will require a rebuild, which is around $850. I had to have the pump off of my 14,000 mile 250SE rebuilt last summer due to the same problem. I sent it to Pacific Fuel Injection in California and they did a wonderful job and were very timely in the rebuild. Good luck!