If spark checks out and timing light shows it to be in the right place, then you'd best turn your attention back to fuel system.

Don't know about Volvo FI specifically, but believe FI are generally sensitive to degredation of electrical connectors and/or temperature sensors. Check for corrosion on all connectors associated with FI related systems and correct as required.

At some point you my consider getting your injectors cleaned. I had very good luck with an outfit called "witchhunter" http:\www.witchhunter.com
I semt 'em the injectors and cold start valve from the Jetta, and the results in starting and running are quite dramatic. Turned around the five parts in about 5 days for about $100 including shipping.

Good luck,
Later,
Al