On the starting problem, has anyone made sure the cold-start injector is actually working? I know you replaced it, maybe no signal to it? I believe you replaced the temp sensor already, that's what controls how long the cold start injector runs, but maybe a wiring or ECM problem is preventing it from working. What they can do is remove the cold start injector, then reconnect the fuel line and electrical connector. Then, using a resistance substitution box simulate a cold engine, MB has a spec for what resistance simulates what temp, and at that particular temp, how long the cold start valve should operate (usually I think it's only in the 1 to 5 second range, so you shouldn't get too much gas sprayed out, in case you're worried about fuel all over the engine.
On the idle, there is a test for the idle control system that they should be doing, it is very cut and dried, shouldn't need to continue throwing parts at the problem. I know it's easy for me to "talk" sitting here in front of my computer, but geez I hate to see parts constantly thrown at a problem like this. Too many part replacers in this world now, not enough mechanics.
If I remember the test correctly, it should be either the valve (which has been done), the ECM (I don't believe this has a seperate idle controller module,it's the CIS control module), or the wiring, but there is an actual idle control test that can and should be done.
Why replace the accumulator, check valve and filter if it passed the pressure and leakdown test? Did they do the volume test too? Good pressure does not automatically indicate good volume! That's like saying that because your battery has 13 volts that it HAS to be able to start your engine. Not true! Sorry if you don't understand the comparison.
Let us know how it's going. I've recently been diagnosed as being "abrasive", so sorry if I seem a little abrasive. I'd really like your your car to operate to your satisfaction as well.
Gilly
ps Go Jack Go!

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