Code 8 is bad throttle position sensor, or connector, or related wiring problem.
Code 11 is bad speed sensor, connector, or related wiring problem.
Now remember that the ECU stores all detected fault codes, unless cleared.
For instance, if you had a throttle position sensor problem a long time ago, and it was fixed, the ECU still has that code logged in addition to the new fault code.
You may have multiple faults, but the only way to be sure is to clear the faults and let it discover them anew.
To clear the faults codes:
1. With the ignition key off, connect a jumper across the green service connector.
2. Turn the ignition key on (as you would to view fault codes).
3. Remove the service connector jumper.
4. The FI indicator will light solid for 5 seconds. During this 5 seconds, reconnect the service connector jumper.
5. The FI light will go off and then start blinking. All fault codes were erased.
6. If the FI light blinks 20 times, the fault codes were not erased. So repeat the previous steps.
Now any fault codes detected will be current.
However, from your initial problem description above, it does sound like a TP sensor related problem.
The bad TP sensor description says the engine behaves poorly when operating the throttle quickly.
Instead of using a known TP sensor position, it used a default 0 deg. position.