Bigger throttle body
 

When you install a bigger TB do you have to tune anything or does the computer adjust itself for more air flow? Still having problem with engine reving on it's own until I slam the gas pedal.

You generally don't need programming. You will need to check the throttle stop screw to insure its set correctly to give you the correct IAC count, idle RPM and TPS voltage. If you go way oversize with an A4, may need some programming adjustments for the shift tables.

You engine isn't going to consume any significant amount of extra air because you go to a larger throttle body. The throttle body will just be able to meet the engine's air requirement at a lower throttle opening.

How do you adjust that? I'm kinda new to this game!

You need a scanner or scan software. Check the idle speed, using the scanner (not the inaacurate stock tach). If its above spec (800rpm for an M6, 650rpm in neutral for an A4) back off the throttle stop screw until the idle speed is within spec. Then using the scanner, check the IAC counts. Should be between 20-40 counts. If they are higher than that, extend the screw to open the blades slightly. If they are lower than that, retract the stop screw to close the blades slightly.

When you are all done, check the closed throttle TPS voltage on the scanner. Should be in the range of 0.20-0.90V. Some people feel a setting of 0.65V is best, but you might have to slot the TPS screw holes to allow the voltage to be adjusted.