Wifi issues since update

[Leather]

Ever since updating to 4.3.1 and all subsequent updates my wifi range has been crap.
It's at a point where if I'm not infront of the router it won't see it.
Before the update there was not a problem. It appears that quite a few people are having the same issues but I've not found any reference to this problem on here.
My iPhone is a 3GS and nearly 2 years old. My wife's iPhone still works perfectly and connects to the router (I haven't updated hers) my sons also connects.
I've restored it as a new phone then updated it straight after.
Not sure what to do next but this is doing my head in now, as where I live, I can't even get 3G.
Can anyone suggest anything??
Thanks in advance.

[stimpy]

If you have your SHSH blobs then you can always downgrade to see if that fixes it.

Or upgrade to 4.3.3 perhaps?

[Leather]

I haven't got the blobs and I've upgraded to 4.3.3 last night.
Might call apple see if they'll have a look.