Engine revs but power not transfered to car

I have a 1998 Toyota Corolla. It is a manual transmission. My issue is when I step on the gas in order to accelerate to merge with traffic on the interstate the engine will rev but the power is not transfered to the car. I have to let up on the pedal and then reapply more conservatively. I am not mashing down on the pedal. This occurs even at the mid position. I have had my car tuned up. Fuel system flushed. Air filter changed. O2 sensors replaced. Catalytic Converter replaced. All this prior to my issue. Is there a problem or is this ok?