BMJR, I must've missed the fact that you had tried to get it diagnosed 'properly'. By bad.

There is an option that has not been mentioned yet. I've had a couple of cars with CIS injection, which is what you have in your car as well. They were Porsches, but essentially the same setup. One of them developed a problem that would let it start okay, but it could not rev properly at all. It got flakier and I tried everything to diagnose. That car did not have a computer, however. Part of the factory procedures run you through every component of fuel injection, and if everything checks out, the recommendation is to replace the fuel distributor. It is the toughest component to test and is the most expensive. I'm guessing a rebuild for our 300 SEL would run somewhere between $300 and $500 for the part. It can be successfully rebuilt if you are reasonably mechanically experienced (even though everyone warns you not to) for just a few dollars. It solved my problem. If you haven't already done so, spend about $18 and buy the Bosch Fuel Injection book which is stocked at the larger bookstores. It has detailed information and procedures.

Hope that helps.