VN Duel Fuel problem

[kaydawgg]

hello. i was wondering if anyone could help me with my car

since we got it it was on duel fuel and we got it roadworthied and fixed, now comes the problem it runs fine on gas but when i change it onto fuel it starts and runs fine but when i take my foot off the accelerator and but it on the brake the cars tries and stalls itself. i was wondering if anyone has any tips or ideas that can help the problem.

[strgas]

check your base idle setting sounds too low

[kaydawgg]

thanks for the reply.

how do i check that, im still learning about cars

[mr calais 5.0]

How old is the petrol and have you changed the fuel filter?

[kaydawgg]

well when we got it roadworthied we got told to run all the old fuel out which we did. now its got brand new fuel in it. and fuel filter i dont think that has been changed. but all that stumbles me is why it only does it on fuel when you take your foot off the accelator