Polo 9n3 throttle body fault?! HELP!!

[Stottie27]

I've got a 2007 polo gti 9n3. Recently whilst driving on the road it shuts down power and goes into limp mode. I ran diagnostics on it and it came up with throttle body mechanical malfunction. I removed it cleaned it ran okay for 50 mikes (ish). But now it's doon the same thing and when it idles it's really lumpy and jumps from between 800 tom to 1400 rpm. Been quoted 540 pounds plus vat for a new body! And a second hand one seems to be impossible to find. Anyone got any ideas or suggestions? Thanks