V star tps

Did you watch the TPS numbers on a scan tool in your car?
TPS code means TPS bad or wiring or TPS adjustment.
Change the TPS as they cost nothing and do wear out.

Did you buy a universal TPS? The one that you removed should have had to round screw holes. Did the new replacement have two round holes as well? If the two screw holes are slotted then you will need to adjust it. Without a scan-tool (to look at like data) it will take longer to adjust. Slide the TPS sensor into place and turn it until the spring and cam wheel starts to move. At this point STOP and tighten the screws. Start the car and test the operation of the sensor. You may need to fine tune the adjustment, be patient. Comparing the performance of the old sensor, to the new one. Is it better or worse then it was. Please write back with any new information or questions, good luck.

Check it on YouTube, there should be one or two show you how to do it yourself.

See this article for adjusting V-Star 1100 TPS
https://docs.google.com/file/d/0B-KrKk_YXL4TRk1vU3lkaW9zM0U/edit?pli=1

The TPS has tamper proof screws but Harbor Freight has a 100 piece set with the right driver for only $8.99
http://www.harborfreight.com/pc-security-bit-set-with-case-68457.html

this code may cause by:

TPS not mounted securely.

TPS circuit short to ground or another wire.

Faulty TPS.

Damaged computer (PCM).

to fix this code you can try this:

Carefully check the throttle position sensor (TPS), wiring connector, and wiring for breaks, etc. Repair or replace as necessary
Check the voltage at the TPS (refer to a service manual for your vehicle for specific information). If the voltage is too low that is indicative of a problem. Replace if necessary.
If recently replaced the TPS may need to be adjusted. On some vehicles the installation instructions call for the TPS to be properly aligned or adjusted, consult a repair manual for specifics.
If there are no symptoms at all, the problem may be intermittent and clearing the code may resolve the issue temporarily. If this is the case then you should definitely check the wiring to be sure it's not rubbing on anything, grounding, etc. The code may come back.

this is an obd2 trouble code table, it can help you understand the meaning of code.
for p0120,
the possible solutions:
If you have access to a scan tool, with KOEO (Key on engine off) observe the TPS voltage. With throttle closed, voltage should be about .45 volts. It should gradually sweep upwards to approximately 4.5 to 5 volts as you depress the throttle. Sometimes only a scope can capture an intermittent glitch in the TPS signal voltage. If you notice a glitch in the TPS sweep voltage, replace the TPS.
NOTE: Some TPS sensors require fine adjustment. If you aren't comfortable with using a DVOM (Digital Volt Ohm meter) to adjust the new TPS, then it's best to take the vehicle to a shop. If the voltage is not .45 volts (+or- .3 volts or so) with the throttle closed or if the reading is "stuck" then unplug the TPS connector. With KOEO check for 5 volts reference voltage present at the connector and a good ground. You can check the signal circuit for continuity by jumping a fused wire between the ground circuit of the TPS connector and the signal circuit. If the TPS reading on the scan tool now reads zero, then replace the TPS. However if that doesn't change the reading to zero, then check for an open or a short on the signal wire and if none is found, suspect a bad PCM. If manipulating the TPS wiring harness causes any change in idle, then suspect bad TPS.

this is an obd2 trouble code table, it can help you understand the meaning of code.
and for p0120
the Causes:
Sticking throttle return spring
MAP or TPS connector corrosion
Misrouted harness causing chafing
Bad TPS
Bad PCM
Possible Solutions:
If you have access to a scan tool, with KOEO (Key on engine off) observe the TPS voltage. With throttle closed, voltage should be about .45 volts. It should gradually sweep upwards to approximately 4.5 to 5 volts as you depress the throttle. Sometimes only a scope can capture an intermittent glitch in the TPS signal voltage. If you notice a glitch in the TPS sweep voltage, replace the TPS.
NOTE: Some TPS sensors require fine adjustment. If you aren't comfortable with using a DVOM (Digital Volt Ohm meter) to adjust the new TPS, then it's best to take the vehicle to a shop. If the voltage is not .45 volts (+or- .3 volts or so) with the throttle closed or if the reading is "stuck" then unplug the TPS connector. With KOEO check for 5 volts reference voltage present at the connector and a good ground. You can check the signal circuit for continuity by jumping a fused wire between the ground circuit of the TPS connector and the signal circuit. If the TPS reading on the scan tool now reads zero, then replace the TPS. However if that doesn't change the reading to zero, then check for an open or a short on the signal wire and if none is found, suspect a bad PCM. If manipulating the TPS wiring harness causes any change in idle, then suspect bad TPS.

I'm assuming you have the 3.3l v-6. When I look up the part, it seems to have slotted holes. Therefore, it is designed to be adjusted after installation. If your tps has these slotted bolt holes, adjust it to satisfy the settings in the test procedure below.

1. Remove air cleaner. Disconnect the TPS harness from the TPS.
2. Using suitable jumper wires, connect a digital voltmeter J-29125-A or equivalent to the correct TPS terminals A and B.
3. With the ignition ON and the engine running, The TPS voltage should be 0.3-1.0 volts at base idle to approximately 4.5 volts at wide open throttle.
4. If the reading on the TPS is out of specification, check the minimum idle speed before replacing the TPS.
5. If the voltage reading is correct, remove the voltmeter and jumper wires and reconnect the TPS connector to the sensor.
6. Reinstall the air cleaner.

There are 2 screws that hold the TPS on to the side of the throttle body. Before you take the old TPS off, note where the TPS is located regarding the adjustment slots. Remove the 2 screws, and remove the old TPS, install the new one, and try to achieve the SAME adjustment. If you get the adjustment wrong, the engine will idle up & down. If it does, move the new TPS slightly until the idle smooths out.