The urgent light is due to the limp home mode kicking in, which will temporarily be reset assuming it can communicate ok with the TPS and/or MAF at the next start-up if you shut it off (as the explanation of your symptoms).
ECM-271A = Fuel adaptation, Bank 2.
ECM-261A = Long-term fuel trim, bank 1, upper limit
ECM-903F = Throttle position (TP) – signal missing (can be generated due to another code triggering limp mode)
ECM-914D = ??
ECM-904C = MIL requested by throttle unit. Faulty signal
ECM-9160 = Throttle unit, internal fault
ECM-9150 = Throttle unit, potentiometer 1. Faulty signal
ECM-510F = Faulty Speed Signal.
That last one is the only one to not add up. You don’t have the ABS light on do you?
To me, I’d start at the basics. Check wiring, by that I mean check that all pins are clean, unbent. Clean the MAF sensor(MAF cleaner specifically), the throttle-body (again, one that’s specifically for it named on the can), and the PCV (throttle-body cleaner works fine). Then check for vacuum leaks since you should have some carb cleaner handy and went through all this trouble anyhow.
Bunch of recalls for this from the bit of reading, further warranty work, and doubtful with all those codes a bit of cleaning will solve it, but worth a shot. Worst case, you clean up parts for the core charge on new ones..
http://www.volvoxc.com/resources/how-to/pdf/fuel-system-electronic-throttle-system-troubleshooting.pdf
http://www.matthewsvolvosite.com/volvo-s70-v70-c70-xc70-s80-1999-trouble-codes (if curious to what the volvo specific codes translate to SAE/ISO wise).