Help Needed iphone 3g no edge signal but working on 3g
 

Can any one shed some light on my wierd situation please.
I currently have an i hpnoe 3g 8 gig. I mistakenly updated to os 4.1 to which i had loads of problems ( no news here ). So i downgraded back to 3.1.3 but stuck with baseband 5.14.02 everything fine untill 2 days ago when my phone suddenly showed no service.I rebooted the phone and voila signal returned for a few minutes. I then found when i went outside i had full 3g signal everything working fine. But when i went indoors the phone signal drooped then started searching then no service. I rang o2 for service status that was fine. Tested other sim cards same problem. I have read the articles here and on the web regarding signal issues and have taken phone appart to see if i have a broken logic board or damaged antenna etc but found no problems even with microscope. I rang apple they said update the firmware, As this seems like a software issue. So i put 4.1 back in and still got the same problem. I am reluctant to go to os 4.2 at this moment. i also emailed iphone repair centre with the reply to update os as no technical reason for this problem ? so before i bite the bullet maybe there is a Genious amongst you good people who can shed some light. P.S jailbroken using sn0wbreeze. Phone is officialy unlocked.:(