Thanks for the posts so far.
Another symptom is - the number of cranks needed to start the engine is directly proportional to how many hours the car has been sitting - after 5-6 hours, it needs 2 cranks, after 12-14 hours, about 4-5. Secondly, while cranking, when it doesn't start, it doesn't do anything else either - what I mean to say is - its not like its hesitating or trying to start - just doesn't do anything (except the cranking noise of course). Could it be a fuel flow problem - leaky fuel line, or leaky fuel pump (the fuel pump should come on when I switch the ignition on, right? its not linked to starting the car)? I plan to take it to my mechanic this monday again, but want to get as much "headstart" before that as possible, because otherwise, it becomes a wild goose chase.
Another questions - do you think the two problems (cold starting, rough cold running) are linked at all?
Also, this is for Steve, what is the differential pressure you were talking about - for diagnostics? I want to understand it before I can ask my tech to do it.
Again, thanks a bunch to everyone who's helping me out.