The thing is that with a phone, you never need a lot of throughput. The throughput can only be tested with USB sticks. So I think you would have the same problem with a phone, if you tested a download with it.
There is no dead end in GPRS. There are so many possible problems that the only limit is your lifespan 🙂
I agree with Jacky, the window size in your PC could slightly limit your throughput. Try doing some TCP/IP optimization (you have some freeware to do that, google “TCP IP optimization)
Gem, other questions:
during your data drivetest…
you observe a peak throughput at 130kb/s : what is the current MCS ?
what is the current number of TS allocated ?
what is the retransmission rate ?
in MCS-6, the max throughput with 4 TS is 30 * 4 = 120kb/s. So probably around 100 or 110 kb/s in real life.
If you are in MCS9 but limited at 120kb/s, then it could be a TCP/IP setting problem.