It's not 22, the Samsung Galaxy S won't lock onto anything of 20 SnR or below unlike HTC Desire/G1 etc.
If you see a grey bar in "GPS Test", that is not a lock on, that is just "I can see this satellite".
The current XXJF3 software seems intent on only using upto 8 satellites, even though you may see 11 all with a good signal, you will only ever use 8.
I wonder if this is half of the problem, it cannot use all the satellites it sees, so when there's a bad signal from a couple in one direction, you lose your lock and it has to try to work frantically to establish a lock elsewhere.
Does XXJF5 allow a lock to more than 8 satellites? Does it open up use to Signal Strength of 20 or below?