Wow, your signals are very strong. How long is the cable from the antenna to your tuner? Is the signal being split at all?
With signals this strong, you might have a problem with signal overload. If you have any amps in the setup, remove them since an overloaded amp will make things worse rather than better.
Even with no amplification, it might still be the case that the signal getting into your tuner card is too strong for it to handle. If that is the case, you may need to add an inline attenuator (like
this one) to lower the signal strength before going into your tuner card.