You might try searching/posting on the
924Board.org :: Index as that is where the majority of the knowledge around the 924 and its CIS system is concentrated around.
As for your #4 problem, I'd verify that your lifters are adjusted properly and that you have good compression on all 4 cylinders.
my 924 came with a bad exhaust valve and I've seen a couple of others with the same issue.
Your vacuum and intake systems are vitally important, make sure there are no vacuum leaks before making CIS adjustments.
Good luck!