I've jailbroken my iPhone 3g since day one (one year ago). I've been experiencing more issues lately what its worth. For examples, the cell/data signals are weak, almost no 3g when compared to iPhones that are not jailbroken in the same room. Phone gets suck and a reboot is required. All iTunes purchased Apps dies after the reboot.
Having the ability to tether via PDANet is nice, running Slingbox over 3g is cool too, but I'm not getting good 3g signals so it makes the apps useless. So I am going to revert back to standard OS 3.0.1.
Are any of you having the same experience/thoughts?
When I got my first 3GS, the jailbreak tools was'nt ready yet, so I used it with the stock firmware.
The reception was okay for a while, and then it developed problem. I would get very weak 3G and wifi signal. Very often I had "No service" for the cell signal too. I went to see the Genius, and they restored the firmware and asked me to monitor it. It was okay for a day, and the problem came back. This is all on stock firmware. I knew it was'nt the Telco's fault because I have my old 3G side by side to make the comparision. The 3G was jailbroken and was having strong 3G and wifi; whereas the 3GS with stock firmware was having unreliable signal strength.
I took all the screen capture to show them the problem, and they gave me a replacement, telling me that is probably from a defective batch with signal reception defect.
On the new 3GS, I have no reception problem either on the stock or jailborken firmware. At one stage, I did have GPS reception problem and thought that I need a second replacement. It turned out that after I did a firmware restore (and I took the opportunity to go from 3.0 to 3.0.1 as well), the GPS signal problem went away for good.
I would say that you may be having a hardware defect that could be confirmed by getting a replacement.