Thermoquad Tuning & Troubleshooting

My rebuilt Thermoquad was working well for awhile now suddenly I am having a few issues with it. First off upon really hammering the accelerator to the floor one of two things occur. Either my engine suddenly runs super rich and stumbles or my accelerator gets stuck in the down position. Mind you, there are no obstructions on my linkage near the transmission nor does my pedal inside the vehicle actually appear jammed. This problem only occurs when I really hammer it to the floor board. Second upon hard breaking my engine stalls. What is going on guys?