02 S60 T5 Turbo Issue

[carniveau]

My 02 S60 T5 has been suffering from a slow spooling turbo now for the last 2 weeks. Per a suggestion I found here I disconnected the MAF and discovered that the turbo would spool up sooner and hold boost for longer, but it also lost about 40% in fuel economy. I have since purchased a new MAF and installed it - no changes to performance. Fuel mileage isn't bad with the MAF connected (25 city to 29/30 highway), starting, idling, no CEL - just poor boost. I also noticed (tell me if this is related to anything) that the fan would continue to run after the car had been driven with the MAF disconnected, but doesn't while it is. Any ideas where I should look next, or has anyone else dealt with this same issue?

Thanks for any advice and/or help,

Ian