Volvo Repair: Volvo S40 hesitation off idle, fuel injector cleaning, vacuum leaks

Question
2004 Volvo S40 1.9l, 110k mi. Engine hesitation when lightly accelerating off idle. Noticeable starting from a stop, or at idle when the a/c compressor comes on. New problem. Recent maint includes new OEM plugs, fuel injector cleaning, fuel filter. No trouble codes stored, no check engine light. Thinking possible EGR valve. No local Volvo dealer. Any ideas where to check next?

Answer
 Don, sorry. Way too many possabilities. Start with the basics. Check for vacuum leaks, run a compression check, test primary and secondary ignition systems. Perform a fuel presuure and volume test. Check all electrical connectors. ETC.
  Driveability problems really are for the MOST skilled techs. You need a lot of fancy (read expensive) test eqwuipment to do the job right. Any fool can swap out a set of brake pads or change a water pump. You need to have a thorough understanding of all the systems and how they interrelate. Or your just guessing with someone else's wallet. For instance, the EGR system is not supposed to be active at idle. It requires partial throttle over a predefined time period before it will engage, typically on decel. You need to know that to repair these vehicles.
  I'll go out on a limb here for you though, I'll bet you lunch at Wendy's that you have a vacuum leak. Unmetered air is entering the system somewhere????? You can mail me a gift certificate when you find it. VVBG

Mark