what kind of problems can cause a misfire of #4 and #5 cap and rotor

replace the cap and rotor.

And wires and plugs and fuel filter and air filter and pcv valve. If the cap and rotor are worn then it's time for a tuneup

A crack or carbon deposits in the distributor cap can cause the miss-fire. They are a cheap product. Replace them, the rotor and points. Think of going to a pointless/transistor style replacement. IF you have a good mechanic, have him check the wires and plugs also. Maybe time to replace them too for good measure.