Wifi and Ethernet Connectivity Issues

Hi everyone,

I have a 2008 Macbook Pro (2.4 GHz, 4 GB RAM, 500 GB HD) running on the newest version of Mavericks software. I have had numerous problems with this Mac (the latest required a new logic board and hard drive) but the latest is that it intermittently drops the wifi or ethernet connection that it is on at a given time. It will be working fine and then seems to randomly drop the connection. I have tried running permissions repair, disk repair, ONYX, removing and re configuring both my wifi and ethernet connections, doing a clean re-install of mavericks (without using time machine), SMC reset, PRAM reset, running a software update, and both quick and long hardware tests (tested normal both times). Apple refuses to see the product (despite them doing all the previous repairs on it earlier this year) because now it is considered a "vintage" product.

The only thing I have found that makes the internet connection work again is to restart the computer. Turning the wifi off and then back on does nothing. Any ideas?

*Update: I was just told by a repair guy that it is the Left I/O Board. Anyone concur? Anyone disagree?