Improved performance after fault code cleared, why?

Car is A4 3.0tdi Quattro 240ps 58 plate, 110k miles. No problems, no dash lights so far.
just had emission light come on and scans showed intake implausible signal. The car still drove as before.
i was unaware of the whole swirl flap issue until now.
fault code was cleared and the car drove so much better than it did before the light came on. 5-6mpg more, much more responsive esp from low revs, but I had not really noticed drop in mpg or responsiveness before. The Light came on again after 1 day and mpg and drop in responsiveness returned.

First question is why would clearing the fault code improve mpg and performance compared to beforehand when there was no fault?

Second question is, has any one fitted the brackets that limit the motor movement sold by DPF Solutions of Sheffield? They claim it prevents the light coming on my limiting the motor movement to within the 2% tolerance.

Third question. Has the swirl flap issue been redesigned in the B9?

Thanks Mand

So I now think improved mpg maybe coincidence due to much warmer weather. Got more than usual mpg just now with light on. Still 2mpg less than when fault was cleared