I have a vitz 99 but the problem is that there is no pick from 0-10 on cng at all while using a/c! On petrol it works fine. I have changed the advancer and wiring (landirenzo) and tuned my car from various places but no good. I got the valves replaced 4 months ago but I got that checked and they have no problem. The plugs air filter etc all checked. Most mechanics told me that this problem can't be solved as it is in every vitz.. If I could get some pro help please?!? And please reply with some surety