i have this codes after installing ls7 tb and intake on my c5
1516-1220-1221-1120
can someone help me please

 

There are letters before the numbers; what do you show? If you have the letters you can look them up here:

http://www.troublecodes.net/OBD2/

or

http://www.obd-codes.com/

If they are 'P' codes, off the top of my head it sounds like you didn't hook up the sensors and traction control.

 

all of them are with p letter

 

From the second link:

P1120 Throttle Position (TP) Sensor 1 Circuit
P1220 Throttle Position (TP) Sensor 2 Circuit
P1221 Throttle Position (TP) Sensor 1- 2 Correlation
P1516 Throttle Actuator Control (TAC) Module Throttle Actuator Position

Performance

 

Yeah this might help...

One unhook your battery and take out our PCM fuse leave unpluged for a bit. Plug everything back in then apply your parking brake and let it idle in drive for 5 minutes then in park for 5 minutes. this will help it relearn its Idle.
Also cleen your MAF with some CRC MAF cleener, If you have a K/N filter it will gunk it up.
After that I dont know because the sensors might be diffrent in that TB might have to put your old sensors in your new TB if you can.