hi folks, i have a mk5a cabby that has some sort of problem, when driving ,usually when idling along if you touch accelerator pedal or even ease of it the car chugs as if running out of petrol, firstly my usual mechanic says throtle response sensor , my old mechanic, say no because it doesnt chug when idling or when you rev it up, he thinks map sensor, anyone any idea as what to try, thanks.