When you get numbers in the 95mbps range in generally means the port is running at 100mbps. This accounts for the small overhead in the data transmission.
If both your pc and router have gigabit ports it is likely the cable. You can check the port setting on your pc to be sure they are set to auto, other setting make it not work at times.
It is really common for a cable to go bad, all it takes is one wire to slightly come loose from one of the ends. But a quality cat5e cable or cat6 is you can get it cheaper. You want the able to be made from pure copper (no CCA) and wire gauge 22-24. Do not buy flat or thin cable.