I haven't said to install the *FSX* service packs, I said to install the SDK first, that will hopefully fix your Simconnect problem without having to reinstall FSX, than install the *SDK* Service Packs.
However, since you don't have the Deluxe version, you can't install the SDK, and you can't update it...
So, I think your only option would be a FSX reinstall, first the base program, then Acceleration (to reinstall everything, you'll need to Uninstall Acceleration first, then Uninstall FSX, then you can start from scratch). Obviously, if you have installed any 3rd party addons, it's probably best to Uninstall *all* those first, then Uninstall Acceleration, then Uninstalll FSX, then reinstall...
If you don't want to do all of this, I think the only option left is to call Microsoft support and try to see if they can help you fixing Simconnect. Unfortunately, there's no separate Simconnect installer except a client in the SDK and, in your case, since you don't have the Deluxe, you don't have the SDK either, so you'll probably need to fix it the hard way.
You might also try Uninstalling Acceleration only, then reinstall it.