It has been a lot of years since we had a CIS car in the shop but about 99% of the time that we had a car that hesatated and usually it was a little lean starting the problem was always the control pressure regulator, also known as the warm up regulator. Some times it was possible to clean it. It is in a tough spot under the intake manifold. there are two fuel lines on the top of it. the larger is the fuel in side. remove fitting and don't loose the two copper washers. spray carb cleaner in to it and let soak a few min. and blow out. You can do this a few times. there is a screen at the bottom and it builds up a fungus on it. (yes a fungus). I have often removed the screen with no side effects. Use a good carb cleaner as some of them wouldn't clean dust from a drinking glass. The sucess rate from cleaning was about 60% so don't be suprised if this didn't work. a new cpr is then required, and here in Florida they are out of sight price wise. I still have the cis injection on my 77 MGB with a B23E engine in it. Because of the cost of CIS parts I'm going to convert it to an LH system when it gives me any problem. Simple fuel pressure testing will verify the problem of the CPR but you really need the Volvo pressure gauge. Good luck.