Choosing capacitors for Microwave RF application
You should be looking for capacitors that exhibit series tuning resonance well above the frequency of interest - the self inductance of the capacitor twinned with its capacitance cause a sharp series resonance. Take a look at this graph from AVX for their MLCC NP0 range in 0805 size: -



More than likely the 10pF will exhibit resonance around the 2 GHz mark. I'd say you either make use of this (because, as an AC coupler it'll still block DC just fine) or find a better grade but for sure you are going to find a lot of caps resonant in the GHz region you want to operate at.