Our response in based on the assumption that your Toyota Solara has a positive short term fuel trim of 99%, as opposed to -99%.
We first recommend removing the PCM fuse to clear the KAM and reset the rear oxygen sensor's short term fuel trim to zero; just in case a fluke in the KAM has triggered positive STFT. We highly recommend this especially if LTFT is within normal range; 3-10% in all operating ranges, idle, 1500 rpm, and 2500 rpm. Keep in mind this will erase your Toyota's emission monitors. You'll need to drive your Solara until it completes a drive cycle in order to reset or complete the monitors.
Should the STFT fault still exist after clearing the KAM, we recommend suspecting the following. Positive short term fuel trim problems are usually caused due to defective Mass Air Flow Sensor (MAF) and/or Oxygen Sensor faults, vacuum leaks, fuel delivery or low pressure issues, dirty or plugged fuel injectors, any unmetered air entering the intake manifold, and failing catalytic converter.
You can test for vacuum leaks using your Toyota's short term and long term fuel data. Measure STFT at idle and than at 2500 RPM. You should notice a correction in STFT at 2500 RPM. While the engine is running rich, STFT should normalize. If you see no data change, look into the possible faults we've mentioned above.
Remember to suspect the CAT only as a final step. It is much more common for a faulty MAF or O2 sensor to cause high STFT than is a bad catalytic converter.
